Lianyang Zhang

Interests

Research

Rock mechanics and rock engineering; Mine ground control; Pile foundations; Geotechnical earthquake engineering; Sustainable geotechnics and geoenvironmental engineering; Waste recycling and utilization; Sustainable and green construction materials; and Eco-friendly dust control.

Teaching

Soil Mechanics; Rock Mechanics; Foundation Engineering; Earth Retaining Structures; Ground Improvement; Geoenvironmental Engineering; and Geotechnical Earthquake Engineering

Courses

Scholarly Contributions

Books

• Zhao, Y., Lin, H., Wang, Y., & Zhang, L. (2021). Hydro-Mechanical Coupling and Creep Behaviours of Geomaterials. Lausanne: Frontiers Media SA.. doi:10.3389/978-2-88966-528-0
• Zhao, Y., Zhang, L., Wang, Y., & Lin, H. (2023). Geofluids: Thermal-Hydraulic-Mechanical (THM) Coupling Behaviour of Fractured Rock Masses. Wiley & Hindawi. doi:https://www.hindawi.com/journals/geofluids/si/506397/
• Zhang, L., Bruno, G. d., & Chen, Z. (2018). Proceedings of GeoShanghai 2018 International Conference: Rock Mechanics and Rock Engineering. Springer.
• Zhang, L. (2017). Engineering Properties of Rocks. Butterworth-Heinemann, Elsevier.
• Ding, W., Zhang, L., Li, X., & Zhang, X. (2014). Proceedings of Geo-Shanghai 2014. ASCE.
• Zhang, L., & Wong, P. L. (2014). ROCK MECHANICS AND ITS APPLICATIONS IN CIVIL, MINING, AND PETROLEUM ENGINEERING. ASCE Publications.
• Zhang, L. (2005). Engineering Properties of Rocks. Elsevier.
• Zhang, L. (2004). Drilled Shafts in Rock – Analysis and Design. A. A. Balkema Publishers.

Chapters

• Li, Z., & Zhang, L. (2016). Fly ash-based geopolymer with kappa-carrageenan biopolymer. In Biopolymers and Biotech Admixtures for Eco-Efficient Construction Materials(pp 173-192).
• Ahmari, S., & Zhang, L. (2014). The properties and durability of alkali-activated masonry units. In Handbook of Alkali-activated Cements, Mortars and Concretes(pp 643--660). Woodhead Publishing.
• Ahmari, S., & Zhang, L. (2014). The properties and durability of mine tailings-based geopolymeric masonry blocks. In Eco-efficient Masonry Bricks and Blocks: Design, Properties and Durability(p. 289). Woodhead Publishing.

Journals/Publications

• Amin Soltanianfard, M., Desai, C. S., Zhang, L., Hosseinali, M., Toufigh, V., & Ghaemian, M. (2023). Experimental Investigation and Constitutive Modeling of Rock-Like Specimens' Interface with the Effect of Roughness Based on 3D Printing. International Journal of Geomechanics, 04023283.
• Chen, H., Hu, J., & Zhang, L. (2023). Three-Dimensional Analyses of Long-Term Settlement of Storage Tanks Supported by a Large Piled-Raft Foundation System. Journal of Geotechnical and Geoenvironmental Engineering, 05023007.
• Chen, H., Zhu, H., & Zhang, L. (2024). Semi???analytical solution for ultimate bearing capacity of smooth and rough circular foundations on rock considering three???dimensional strength. International Journal for Numerical and Analytical Methods in Geomechanics.
• Korouzhdeh, T., Eskandari-Naddaf, H., Shadnia, R., & Zhang, L. (2024). A comparative study between Gray Wolf and particle swarm algorithms use for optimization of cost in composite beam. Soft Computing, 1-23.
• Nikvar-Hassani, A., Batchler, T., & Zhang, L. (2024). Full-Scale Demonstration and Performance Evaluation of a Hybrid Geopolymer/Biopolymer Cementitious Material Developed for Pumpable Roof Supports in Underground Mines. Mining, Metallurgy & Exploration, 1-12.
• Nikvar-Hassani, A., Chen, H., Motameni, S., Visnansky, C., Lovelady, M., Cutruzzula, S. E., & Zhang, L. (2024). Using cross-linked polyethylene (XLPE) waste in production of concrete: An experimental study. Construction and Building Materials, 411, 134261.
• Chen, H., & Zhang, L. (2023). Reply to Discussion on "A Machine Learning-Based Method for Predicting End-Bearing Capacity of Rock-Socketed Shafts" [Rock Mech Rock Eng 55, 1743-1757]. Rock Mechanics and Rock Engineering, 1-3.
• Chen, H., Nikvar-Hassani, A., Ormsby, S., Ramey, D., & Zhang, L. (2023). Mechanical and microstructural investigations on the low-reactive copper mine tailing-based geopolymer activated by phosphoric acid. Construction and Building Materials, 393, 132030.
• Chen, H., Zhu, H., & Zhang, L. (2023). Rock Slope Stability Analysis Incorporating the Effects of Intermediate Principal Stress. Rock Mechanics and Rock Engineering, 1-19.
• Xu, Q., Xie, J., Zhang, L., He, X., Lu, L., & Li, Y. (2023). Failure analysis of progressive instability and deformation law of excavation face in sand cobble stratum under cutting disturbance by shield cutter. Engineering Failure Analysis, 154, 107711.
• Zhao, Y., Liu, J., Zhang, C., Zhang, H., Liao, J., Zhu, S., & Zhang, L. (2023). Mechanical behavior of sandstone during post-peak cyclic loading and unloading under hydromechanical coupling. International Journal of Mining Science and Technology, 33(8), 927-947.
• Zhao, Y., Wang, X., Tang, W., Li, Y., Lin, H., Wang, Y., & Zhang, L. (2023). Creep behavior of layered salt rock under triaxial loading and unloading cycles. Applied Rheology, 33(1), 20230103.
• Zhao, Y., Zhang, L., Wang, Y., & Lin, H. (2023). Editorial: Thermal-Hydraulic-Mechanical (THM) Coupling Behaviour of Fractured Rock Masses. Geofluids, 2023, 1-4. doi:https://doi.org/10.1155/2023/9764934
• Chen, H., & Zhang, L. (2022). A machine learning-based method for predicting end-bearing capacity of rock-socketed shafts. Rock Mechanics and Rock Engineering, 55(3), 1743-1757.
• Chen, H., Zhu, H., & Zhang, L. (2022). A Three-Dimensional (3D) Semi-analytical Solution for the Ultimate End-Bearing Capacity of Rock-Socketed Shafts. Rock Mechanics and Rock Engineering, 55(2), 611-627.
• Chen, H., Zhu, H., & Zhang, L. (2022). A three-dimensional (3D) analytical solution for the ultimate side shear resistance of rock-socketed shafts. International Journal of Rock Mechanics and Mining Sciences, 159, 105231.
• Chen, H., Zhu, H., & Zhang, L. (2022). An analytical approach to the ultimate bearing capacity of smooth and rough strip foundations on rock mass considering three-dimensional (3D) strength. Computers and Geotechnics, 149, 104865.
• Chen, H., Zhu, H., & Zhang, L. (2022). Further modification of a generalised 3D Hoek–Brown criterion: the GZZ criterion. Geotechnique Letters, 12(4), 272-280.
• Kazemi, R., Shadnia, R., Eskandari-Naddaf, H., & Zhang, L. (2022). The Properties of Cement-Mortar at Different Cement Strength Classes: Experimental Study and Multi-objective Modeling. Arabian Journal for Science and Engineering, 1-16.
• Liu, J., Zhao, Y., Tan, T., Zhang, L., Zhu, S., & Xu, F. (2022). Evolution and modeling of mine water inflow and hazard characteristics in southern coalfields of China: A case of Meitanba mine. International Journal of Mining Science and Technology.
• Nikvar-Hassani, A., & Zhang, L. (2022). Development of a biopolymer modified geopolymer based cementitious material for enhancement of pumpable roof support. Materials and Structures, 55(4), 1-22.
• Nikvar-Hassani, A., & Zhang, L. (2022). Synthesis of a CKD modified fly ash based geopolymer cementitious material for enhancing pumpable roof support. Materials and Structures, 55(2), 1-24.
• Nikvar-Hassani, A., Alnuaimi, H. N., Amjad, U., Sasmal, S., Zhang, L., & Kundu, T. (2022). Alkali Activated Fly Ash-Based Concrete: Evaluation of Curing Process Using Non-Linear Ultrasonic Approach. Journal of Nondestructive Evaluation, Diagnostics and Prognostics of Engineering Systems, 5(2).
• Nikvar-Hassani, A., Hodges, R., & Zhang, L. (2022). Production of green bricks from low-reactive copper mine tailings: Durability and environmental aspects. Construction and Building Materials, 337, 127571.
• Nikvar-Hassani, A., Manjarrez, L., & Zhang, L. (2022). Rheology, Setting Time, and Compressive Strength of Class F Fly Ash–Based Geopolymer Binder Containing Ordinary Portland Cement. Journal of Materials in Civil Engineering, 34(1), 04021375.
• Nikvar-Hassani, A., Vashaghian, H., Hodges, R., & Zhang, L. (2022). Production of green bricks from low-reactive copper mine tailings: Chemical and mechanical aspects. Construction and Building Materials, 324, 126695.
• Alnuaimi, H. N., Sasmal, S., Amjad, U., Nikvar-Hassani, A., Zhang, L., & Kundu, T. (2021). Monitoring Concrete Curing by Linear and Nonlinear Ultrasonic Methods. ACI Materials Journal, 118(3), 61-69.
• Cai, W., Zhu, H., Liang, W., Zhang, L., & Wu, W. (2021). A New Version of the Generalized Zhang–Zhu Strength Criterion and a Discussion on Its Smoothness and Convexity. Rock Mechanics and Rock Engineering, 1-17.
• Chen, H., Zhu, H., & Zhang, L. (2021). A Unified Constitutive Model for Rock Based on Newly Modified GZZ Criterion. Rock Mechanics and Rock Engineering, 54(2), 921-935.
• Chen, H., Zhu, H., & Zhang, L. (2021). Analytical solution for deep circular tunnels in rock with consideration of disturbed zone, 3D strength and large strain. Rock Mechanics and Rock Engineering, 54(3), 1391-1410.
• Sadat, M. R., Muralidharan, K., Frantziskonis, G. N., & Zhang, L. (2021). From atomic-scale to mesoscale: A characterization of geopolymer composites using molecular dynamics and peridynamics simulations. Computational Materials Science, 186, 110038.
• Wang, X., Zhu, H., Zhu, M., Zhang, L., & Ju, J. W. (2021). An integrated parameter prediction framework for intelligent TBM excavation in hard rock. Tunnelling and Underground Space Technology, 118, 104196.
• Zhang, L., Chen, R., Ding, X., & Lai, H. (2021). Improving dust resistance of mine tailings using green biopolymer. Environmental Geotechnics, 8(6), 382-391. doi:10.1680/jenge.18.00089
• Zhao, Y., Zhang, L., & Wang, Y. (2021). Editorial: Hydro-Mechanical Coupling and Creep Behaviors of Geomaterials. Frontiers in Earth Science, 8, doi-10.
• An, M., Zhang, F., Chen, Z., Elsworth, D., & Zhang, L. (2020). Temperature and fluid pressurization effects on frictional stability of shale faults reactivated by hydraulic fracturing in the Changning block, southwest China. Journal of Geophysical Research: Solid Earth, 125(8), e2020JB019584.
• An, M., Zhang, F., Elsworth, D., Xu, Z., Chen, Z., & Zhang, L. (2020). Friction of Longmaxi Shale Gouges and Implications for Seismicity During Hydraulic Fracturing. Journal of Geophysical Research: Solid Earth, 125(8), e2020JB019885.
• Xu, Q., Zhang, L., Zhu, H., Gong, Z., Liu, J., & Zhu, Y. (2020). Laboratory tests on conditioning the sandy cobble soil for EPB shield tunnelling and its field application. Tunnelling and Underground Space Technology, 105, 103512.
• Yin, Z., Huang, H., Zhang, F., Zhang, L., & Maxwell, S. (2020). Three-dimensional distinct element modeling of fault reactivation and induced seismicity due to hydraulic fracturing injection and backflow. Journal of Rock Mechanics and Geotechnical Engineering, 12(4), 752-767.
• Zhang, F., An, M., Zhang, L., Fang, Y., & Elsworth, D. (2020). Effect of mineralogy on friction-dilation relationships for simulated faults: Implications for permeability evolution in caprock faults. Geoscience Frontiers, 11(2), 439-450.
• Zhang, F., Yin, Z., Chen, Z., Maxwell, S., Zhang, L., & Wu, Y. (2020). Fault Reactivation and Induced Seismicity During Multistage Hydraulic Fracturing: Microseismic Analysis and Geomechanical Modeling. SPE Journal, 25(02), 692-711.
• Zhang, J., Zhang, L., Wang, W., Zhang, D., & Zhang, B. (2020). Probabilistic analysis of three-dimensional tunnel face stability in soft rock masses using Hoek-Brown failure criterion. International Journal for Numerical and Analytical Methods in Geomechanics, 44(11), 1601-1616.
• Zhang, K., Wu, W., Zhu, H., Zhang, L., Li, X., & Zhang, H. (2020). A modified method of discontinuity trace mapping using three-dimensional point clouds of rock mass surfaces. Journal of Rock Mechanics and Geotechnical Engineering, 12(3), 571-586.
• Zhao, Y., Zhang, L., Liao, J., Wang, W., Liu, Q., & Tang, L. (2020). Experimental Study of Fracture Toughness and Subcritical Crack Growth of Three Rocks under Different Environments. International Journal of Geomechanics, 20(8), 04020128.
• Zhao, Y., Zhang, L., Wang, W., Liu, Q., Tang, L., & Cheng, G. (2020). Experimental Study on Shear Behavior and a Revised Shear Strength Model for Infilled Rock Joints. International Journal of Geomechanics, 20(9), 04020141.
• Zhu, H., Wang, X., Chen, X., & Zhang, L. (2020). Similarity search and performance prediction of shield tunnels in operation through time series data mining. Automation in Construction, 114, 103178.
• Gur, S., Sadat, M. R., Frantziskonis, G., Bringuier, S., Zhang, L., & Muralidharan, K. (2019). The effect of grain-size on fracture of polycrystalline silicon carbide: A multiscale analysis using a molecular dynamics-peridynamics framework. Computational Materials Science, 159, 341-348.
• Lai, H., Zhang, J., Zhang, L., Chen, R., & Yang, W. (2019). A new method based on centrifuge model test for evaluating ground settlement induced by tunneling. KSCE Journal of Civil Engineering, 23, 2426-2436.
• Manjarrez, L., Nikvar-Hassani, A., Shadnia, R., & Zhang, L. (2019). Experimental Study of Geopolymer Binder Synthesized with Copper Mine Tailings and Low-Calcium Copper Slag. JOURNAL OF MATERIALS IN CIVIL ENGINEERING, 31(8).
• Ren, X., & Zhang, L. (2019). Experimental Study of Geopolymer Concrete Produced from Waste Concrete. JOURNAL OF MATERIALS IN CIVIL ENGINEERING, 31(7).
• Wang, P., Shi, Y., Zhang, L., & Li, Y. (2019). Effect of structural parameters on atomization characteristics and dust reduction performance of internal-mixing air-assisted atomizer nozzle. PROCESS SAFETY AND ENVIRONMENTAL PROTECTION, 128, 316-328.
• Wang, P., Tan, X., Zhang, L., Li, Y., & Liu, R. (2019). Influence of particle diameter on the wettability of coal dust and the dust suppression efficiency via spraying. PROCESS SAFETY AND ENVIRONMENTAL PROTECTION, 132, 189-199.
• Zhang, F., An, M., Zhang, L., Fang, Y. i., & Elsworth, D. (2019). The Role of Mineral Composition on the Frictional and Stability Properties of Powdered Reservoir Rocks. JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH, 124(2), 1480-1497.
• Madadi, A., Eskandari-Naddaf, H., Shadnia, R., & Zhang, L. (2018). Characterization of ferrocement slab panels containing lightweight expanded clay aggregate using digital image correlation technique. Construction and Building Materials, 180, 464-474.
• Madadi, A., Eskandari-Naddaf, H., Shadnia, R., & Zhang, L. (2018). Digital image correlation to characterize the flexural behavior of lightweight ferrocement slab panels. Construction and Building Materials, 189, 967-977.
• Manjarrez, L., & Zhang, L. (2018). Utilization of copper mine tailings as road base construction material through geopolymerization. Journal of Materials in Civil Engineering, 30(9), 04018201.
• Ren, X., & Zhang, L. (2018). Experimental study of interfacial transition zones between geopolymer binder and recycled aggregate. Construction and Building Materials, 167, 749-756.
• Sadat, M. R., Bringuier, S., Muralidharan, K., Frantziskonis, G., & Zhang, L. (2018). Atomic-scale dynamics and mechanical response of geopolymer binder under nanoindentation. Computational Materials Science, 142, 227-236.
• Sadat, M. R., Muralidharan, K., & Zhang, L. (2018). Reactive molecular dynamics simulation of the mechanical behavior of sodium aluminosilicate geopolymer and calcium silicate hydrate composites. Computational Materials Science, 150, 500-509.
• Zhang, L., & Manjarrez, L. (2018). Utilization of Copper Mine Tailings as Road Base Construction Material through Geopolymerization. Journal of Materials in Civil Engineering, 30(9). doi:10.1061/(asce)mt.1943-5533.0002397
• Zhang, L., & Zhao, Y. (2018). Experimental Study on the Mud-Water Inrush Characteristics through Rock Fractures. Advances in Civil Engineering, 2018, 1-7. doi:10.1155/2018/2060974
• Zhao, Y., & Zhang, L. (2018). Experimental study on the mud-water inrush characteristics though rock fractures. Advances in Civil Engineering, 1-7.
• Zhao, Y., Ma, W., Zhang, L., Li, S., & Yang, H. (2018). Separation of elasto-visco-plastic strains of rock and a nonlinear creep model. International Journal of Geomechanics, 18(1), 04017129.
• Chen, R., Ding, X., Zhang, L., Xie, Y., & Lai, H. (2017). Discrete element simulation of mine tailings stabilized with biopolymer. Environmental Earth Sciences, 76, 772.
• Shadnia, R., & Zhang, L. (2017). Experimental study of geopolymer synthesized with class F fly ash and low calcium slag. Journal of Materials in Civil Engineering, 29(10), 04017195.
• Zhang, L. (2017). Evaluation of rock mass deformability using empirical methods--A review. Underground Space.
• Zhang, L., & Shadnia, R. (2017). Experimental Study of Geopolymer Synthesized with Class F Fly Ash and Low-Calcium Slag. Journal of Materials in Civil Engineering, 29(10). doi:10.1061/(asce)mt.1943-5533.0002065
• Zhao, W. (2017). Transient pulse test and morphological analysis of single rock fractures. International Journal of Rock Mechanics & Mining Sciences, 91, 139--154.
• Zhao, Y., Luo, S., Wang, Y., Wang, W., Zhang, L., & Wan, W. (2017). Numerical Analysis of Karst Water Inrush and a Criterion for Establishing the Width of Water-resistant Rock Pillars. Mine Water and the Environment, 1--12.
• Zhao, Y., Tang, J., Chen, Y. u., Zhang, L., Wang, W., Wan, W., & Liao, J. (2017). Hydromechanical coupling tests for mechanical and permeability characteristics of fractured limestone in complete stress--strain process. Environmental Earth Sciences, 76(1), 24.
• Zhao, Y., Zhang, L., Luo, S., Wang, W., Wan, W., Li, S., Ma, W., & Wang, Y. (2017). Creep behavior of intact and cracked limestone under multi-level loading and unloading cycles. Rock Mechanics and Rock Engineering, 50(6), 1409-1424.
• Zhu, H., Zhang, Q., Huang, B., & Zhang, L. (2017). A constitutive model based on the modified generalized three-dimensional Hoek–Brown strength criterion. International Journal of Rock Mechanics and Mining Science, 98, 78-87.
• Cai, Y., Han, L., Tian, L., & Zhang, L. (2016). Meshless method based on Shepard function and partition of unity for two-dimensional crack problems. Engineering Analysis with Boundary Elements, 65, 126--135.
• Chen, J., Zeng, F., Wang, J., & Zhang, L. (2017). Analysis of Laterally Loaded Rock-Socketed Shafts Considering the Nonlinear Behavior of Both the Soil/Rock Mass and the Shaft. Journal of Geotechnical and Geoenvironmental Engineering, 06016025.
• Chen, R., Ding, X., Ramey, D., Lee, I., & Zhang, L. (2016). Experimental and numerical investigation into surface strength of mine tailings after biopolymer stabilization. Acta Geotechnica, 11(5), 1075--1085.
• Chen, R., Ramey, D., Weiland, E., Lee, I., & Zhang, L. (2016). Experimental Investigation on Biopolymer Strengthening of Mine Tailings. Journal of Geotechnical and Geoenvironmental Engineering, 142(12), 06016017.
• Sadat, M. R., Bringuier, S., Asaduzzaman, A., Muralidharan, K., & Zhang, L. (2016). A molecular dynamics study of the role of molecular water on the structure and mechanics of amorphous geopolymer binders. The Journal of Chemical Physics, 145(13), 134706.
• Sadat, M. R., Bringuier, S., Muralidharan, K., Runge, K., Asaduzzaman, A., & Zhang, L. (2016). An atomistic characterization of the interplay between composition, structure and mechanical properties of amorphous geopolymer binders. Journal of Non-Crystalline Solids, 434, 53--61.
• Zhang, L. (2016). Determination and applications of rock quality designation (RQD). Journal of Rock Mechanics and Geotechnical Engineering, 8(3), 389--397.
• Zhao, Y., Zhang, L., Wang, W., Pu, C., Wan, W., & Tang, J. (2016). Cracking and Stress--Strain Behavior of Rock-Like Material Containing Two Flaws Under Uniaxial Compression. Rock Mechanics and Rock Engineering, 49(7), 2665--2687.
• Zhou, S., Zhu, H., Yan, Z., Ju, J. W., & Zhang, L. (2016). A micromechanical study of the breakage mechanism of microcapsules in concrete using PFC2D. Construction and Building Materials, 115, 452--463.
• Zhu, H., Huang, X., Li, X., Zhang, L., & Liu, X. (2016). Evaluation of urban underground space resources using digitalization technologies. Underground Space, 1(2), 124--136.
• Ahmari, S., Parameswaran, K., & Zhang, L. (2015). Alkali Activation of Copper Mine Tailings and Low-Calcium Flash-Furnace Copper Smelter Slag. Journal of Materials in Civil Engineering, 10--1061.
• Asaduzzaman, A., Runge, K., Muralidharan, K., Deymier, P. A., & Zhang, L. (2015). Energetics of substituted polyhedral oligomeric silsesquioxanes: a DFT study. MRS Communications, 5(03), 519--524.
• Chen, R., Lee, I., & Zhang, L. (2015). Biopolymer Stabilization of Mine Tailings for Dust Control. Journal of Geotechnical and Geoenvironmental Engineering, 141(2), 04014100.
• Meng, Z., Chen, J., Zhang, L., Wang, J., & Yao, J. (2015). Field tests to investigate the installation effects of drilled displacement piles with screw-shaped shaft in clay. Journal of Geotechnical and Geoenvironmental Engineering, 141(12), 06015010.
• Ren, X., Zhang, L., Ramey, D., Waterman, B., & Ormsby, S. (2015). Utilization of aluminum sludge (AS) to enhance mine tailings-based geopolymer. Journal of Materials Science, 50(3), 1370--1381.
• Shadnia, R., Zhang, L., & Li, P. (2015). Experimental study of geopolymer mortar with incorporated PCM. Construction and Building Materials, 84, 95--102.
• Zhang, L., Ahmari, S., & Parameswaran, K. (2015). Alkali Activation of Copper Mine Tailings and Low-Calcium Flash-Furnace Copper Smelter Slag. Journal of Materials in Civil Engineering, 27(6). doi:10.1061/(asce)mt.1943-5533.0001159
• Zhang, L., Chen, R., & Lee, I. (2015). Biopolymer Stabilization of Mine Tailings for Dust Control. Journal of Geotechnical and Geoenvironmental Engineering, 141(2). doi:10.1061/(asce)gt.1943-5606.0001240
• Zhang, Q., Zhu, H., & Zhang, L. (2015). Studying the effect of non-spherical micro-particles on Hoek--Brown strength parameter mi using numerical true triaxial compressive tests. International Journal for Numerical and Analytical Methods in Geomechanics, 39(1), 96--114.
• Chen, R., Ahmari, S., & Zhang, L. (2014). Utilization of sweet sorghum fiber to reinforce fly ash-based geopolymer. Journal of Materials Science, 49(6), 2548-2558.
  More info

  Abstract: Geopolymer has been of great research interest as a material for sustainable development. As ordinary Portland cement, however, geopolymer exhibits brittle behavior with low tensile strength, ductility, and fracture toughness. This paper investigates the reinforcement of fly ash-based geopolymer with alkali-pretreated sweet sorghum fiber. The sweet sorghum fiber comes from the bagasse (residue), a waste after the juice is extracted from sweet sorghum stalks for ethanol production. Specifically, the unit weight of fly ash-based geopolymer specimens containing different contents of sweet sorghum fibers was measured. Unconfined compression, splitting tensile, and flexural tests were conducted to investigate the effect of incorporated sweet sorghum fiber on the mechanical properties of fly ash-based geopolymer. Scanning electron microscopy imaging was also performed to study the microstructure of the sweet sorghum fiber-geopolymer composite. The results indicate that the unit weight of the sweet sorghum fiber-geopolymer composite decreases with higher fiber content. Although the inclusion of sweet sorghum fiber slightly decreases the unconfined compressive strength, the splitting tensile, and flexural strengths as well as the post-peak toughness increase with the fiber content up to 2 % and then start to decrease. The splitting tensile tests also clearly show the transition from the brittle failure of the plain geopolymer specimen to the "ductile" failure of the geopolymer specimen containing sweet sorghum fiber. © 2013 Springer Science+Business Media New York.
• Ding, X., & Zhang, L. (2014). A new contact model to improve the simulated ratio of unconfined compressive strength to tensile strength in bonded particle models. International Journal of Rock Mechanics and Mining Sciences, 69, 111--119.
• Ding, X., Zhang, L., Zhu, H., & Zhang, Q. (2014). Effect of Model Scale and Particle Size Distribution on PFC3D Simulation Results. Rock Mechanics and Rock Engineering, 1-18.
  More info

  Abstract: This paper investigates the effect of model scale and particle size distribution on the simulated macroscopic mechanical properties, unconfined compressive strength (UCS), Young's modulus and Poisson's ratio, using the three-dimensional particle flow code (PFC3D). Four different maximum to minimum particle size (dmax/dmin) ratios, all having a continuous uniform size distribution, were considered and seven model (specimen) diameter to median particle size ratios (L/d) were studied for each dmax/dmin ratio. The results indicate that the coefficients of variation (COVs) of the simulated macroscopic mechanical properties using PFC3D decrease significantly as L/d increases. The results also indicate that the simulated mechanical properties using PFC3D show much lower COVs than those in PFC2D at all model scales. The average simulated UCS and Young's modulus using the default PFC3D procedure keep increasing with larger L/d, although the rate of increase decreases with larger L/d. This is mainly caused by the decrease of model porosity with larger L/d associated with the default PFC3D method and the better balanced contact force chains at larger L/d. After the effect of model porosity is eliminated, the results on the net model scale effect indicate that the average simulated UCS still increases with larger L/d but the rate is much smaller, the average simulated Young's modulus decreases with larger L/d instead, and the average simulated Poisson's ratio versus L/d relationship remains about the same. Particle size distribution also affects the simulated macroscopic mechanical properties, larger dmax/dmin leading to greater average simulated UCS and Young's modulus and smaller average simulated Poisson's ratio, and the changing rates become smaller at larger dmax/dmin. This study shows that it is important to properly consider the effect of model scale and particle size distribution in PFC3D simulations. © 2013 Springer-Verlag Wien.
• Zhang, L., Zhang, Q., & Zhu, H. (2014). Studying the effect of non-spherical micro-particles on Hoek-Brown strength parameter m_i using numerical true triaxial compressive tests: EFFECT OF NON-SPHERICAL MICRO-PARTICLES ON H-B STRENGTH PARAMETER m_i . International Journal for Numerical and Analytical Methods in Geomechanics, 39(1), 96-114. doi:10.1002/nag.2310
• Ahmari, S., & Zhang, L. (2013). Durability and leaching behavior of mine tailings-based geopolymer bricks. Construction and Building Materials, 44, 743-750.
  More info

  Abstract: Disposal of mine tailings (MT) in impoundments may have adverse environmental impacts such as air pollution from dust emissions and release of heavy metals to surface and underground water. Geopolymerization as an environmentally-friendly and sustainable method has been used to stabilize MT so that they can be used as construction material. In this paper, the durability and leaching behavior of MT-based geopolymer bricks are studied by measuring unconfined compression strength (UCS), water absorption, weight loss, and concentration of heavy metals after immersion in pH = 4 and 7 solutions for different periods of time. Microscopic/spectroscopic techniques, SEM, XRD and FTIR, are also employed to investigate the change in microstructure and phase composition of MT-based geopolymer bricks after immersion in the solutions. To describe the leaching behavior of MT-based geopolymer bricks, the first order reaction/diffusion model (FRDM) is used to analyze the leaching test data. The results indicate that although there is a substantial strength loss after immersion in pH = 4 and 7 solutions, the water absorption and weight loss are small. The strength loss is mainly due to the dissolution of geopolymer gels as indicated by the microscopic/spectroscopic analysis results. The leaching analyses show that the heavy metals are effectively immobilized in the MT-based geopolymer bricks, which is attributed to the incorporation of heavy metals in the geopolymer network. The FRDM can satisfactorily describe the leaching behavior of heavy metals in the MT-based geopolymer bricks and the analysis results indicate that the solubility or reaction rate is an important factor controlling the leaching behavior. © 2013 Elsevier Ltd. All rights reserved.
• Ahmari, S., & Zhang, L. (2013). Utilization of cement kiln dust (CKD) to enhance mine tailings-based geopolymer bricks. Construction and Building Materials, 40, 1002-1011.
  More info

  Abstract: This paper studies the feasibility of enhancing the physical and mechanical properties and the durability of copper mine tailings (MT)-based geopolymer bricks with cement kiln dust (CKD). The effects of CKD content (0-10%), sodium hydroxide (NaOH) concentration (10 and 15 M) and initial water content (12-20%) on unconfined compressive strength (UCS), water absorption, and weight and strength losses after immersion in water are studied. To shed light on the mechanism for the contribution of CKD to geopolymerization, microscopic and spectroscopic techniques including scanning electron microscopy/energy- dispersive X-ray spectroscopy (SEM/EDX), X-ray diffraction (XRD), and Fourier transform infrared (FTIR) spectroscopy are used to investigate the micro/nanostructure and the elemental and phase composition of geopolymer brick specimens. The results show significant improvement of UCS and durability when CKD is used. Water absorption, however, slightly increases due to the hydration of Ca in the added CKD. The enhancement of UCS and durability is attributed to the improving effect of CKD on dissolution of aluminosilicate species, formation of CaCO3, and integration of Ca into the geopolymer gel. © 2012 Elsevier Ltd. All rights reserved.
• Budhu, M., Zhang, L., & Chen, R. (2013). Biopolymer Stabilization of Mine Tailings. Journal of Geotechnical and Geoenvironmental Engineering, 139(10), 1802-1807. doi:10.1061/(asce)gt.1943-5606.0000902
• Chen, J., & Zhang, L. (2013). Effect of spatial correlation of cone tip resistance on the bearing capacity of piles. Journal of Geotechnical and Geoenvironmental Engineering, 139(3), 494-500.
  More info

  Abstract: The cone tip resistance (qc) from cone penetration tests (CPTs) is widely used to determine the bearing capacity of piles. Although it is widely known that soil properties are spatially correlated, the spatial correlation of qc is not considered in the current methods for predicting the bearing capacity of piles. In this paper, a probabilistic approach is presented for predicting the bearing capacity of driven piles in clay by considering the spatial correlation between qcsVn (the spatial average of qc of the bottom soil layer within the pile length) and qcbV (the spatial average of qc over an interval near the pile base). Parametric studies are conducted to evaluate the effect of the spatial correlation between qcsVn and qcbV on the bearing capacity of piles. The results indicate that it is important to consider the spatial correlation between qcsVn and qcbV in the probabilistic prediction of the bearing capacities of piles. Ignoring the spatial correlation between qcsVn and qcbV will underestimate the probability of failure and lead to unsafe design. Finally, 14 field test piles are analyzed with the presented approach to demonstrate the probabilistic prediction of the bearing capacity of piles by considering the spatial correlation of the CPT data. © 2013 American Society of Civil Engineers.
• Chen, J., Zhang, L., Zhang, J., Zhu, Y., & Wang, J. (2013). Field tests, modification, and application of deep soil mixing method in soft clay. Journal of Geotechnical and Geoenvironmental Engineering, 139(1), 24-34.
  More info

  Abstract: The installation of soil-cement columns causes excess pore-water pressures and movements of surrounding ground, which affect adjacent underground structures. In Shanghai, a triple-shaft deep soil mixing (DSM) method has been proposed and is widely used to minimize the installation effects. However, when this DSM method was used to install soil-cement columns close to a Metro tunnel, unacceptable soil displacement was caused, even at the very beginning. Therefore, it was decided to conduct field tests to investigate the effect of major factors affecting DSM installations and then modify the construction parameters so that the soil displacement caused by DSM construction would not exceed the allowable limit. The field tests consisted of two phases: Phase I tests of single DSM column installations close to the Metro tunnel to modify the construction parameters, and Phase II tests of continuous multiple DSM column installations far from the Metro tunnel to validate the modified construction parameters. Detailed pore-water pressure and soil displacement measurements were conducted during the field tests. Based on the field tests, the traditional DSM method was modified by using a higher water/cement ratio, lower mixing speed, and no injection during withdrawal, and adopting a new installation sequence for continuous construction that started from the farthest row and moved closer to the tunnel. Using the modified construction parameters, the triple-shaft DSM method was successfully applied to the large-scale soil improvement of an underground highway excavation project close to the Metro tunnels. This paper describes the background, the field tests, the modified DSM method, and its successful application. © 2013 American Society of Civil Engineers.
• Chen, R., Zhang, L., & Budhu, M. (2013). Biopolymer stabilization of mine tailings. Journal of Geotechnical and Geoenvironmental Engineering, 139(10), 1802-1807.
  More info

  Abstract: A feasibility study was performed on using xanthan gum and guar gum, two biopolymers that are naturally occurring and inexpensive, to stabilize mine tailings (MT). The simple fall cone method was adopted to evaluate the liquid limit and undrained shear strength of sundried MT mixed with xanthan gum or guar gum solutions at different concentrations. Environmental scanning electron microscopy (ESEM) imaging was also conducted to study the microstructure of the biopolymer-MT system. The results indicate that the inclusion of xanthan gum or guar gum increases both the liquid limit and the undrained shear strength of the MT, higher biopolymer concentrations leading to greater increases. The increase of the liquid limit and undrained shear strength of the MT mixed with a biopolymer solution is mainly attributable to the high viscosity of the biopolymer pore fluid and the bonding between the biopolymer and the MT particles. Guar gum is more effective than xanthan gum in increasing the liquid limit and undrained shear strength of the MT, because the guar gum solution is more viscous than the xanthangumsolution at the same concentration, the guargum-MTparticle bonding is stronger than the xanthan gum-MTparticle bonding, and guar gum causes a lower degree of aggregation of MT particles than xanthan gum. By comparing the undrained shear strength data with empirical equations in the literature, two new equations were proposed for predicting the undrained shear strength of the MT mixed with a biopolymer for water contents near the liquid limit, based on the liquid limit and water content, and the liquidity index, respectively. © 2013 American Society of Civil Engineers.
• Zhang, L. (2013). Aspects of rock permeability. Frontiers of Structural and Civil Engineering, 7(2), 102-116.
  More info

  Abstract: Effective evaluation of rock permeability is required in different energy, engineering and environmental projects. Although much research has been conducted on rock permeability, it is still one of the most difficult tasks for practicing rock engineers to accurately determine rock permeability. Based on a comprehensive literature review, this paper outlines the key aspects of rock permeability by presenting the representative values of the permeability of different rocks, describing the empirical and semi-empirical correlations for estimating the permeability of rocks, and discussing the main factors affecting the permeability of rocks. The factors discussed include stress, depth, temperature, and discontinuity intensity and aperture. This paper also highlights the scale effect on rock permeability, interconnectivity of discontinuities, and anisotropy of rock permeability. This paper provides the fundamental and essential information required for effective evaluation of rock permeability. © 2013 Higher Education Press and Springer-Verlag Berlin Heidelberg.
• Zhang, L. (2013). Production of bricks from waste materials - A review. Construction and Building Materials, 47, 643-655.
  More info

  Abstract: Bricks are a widely used construction and building material around the world. Conventional bricks are produced from clay with high temperature kiln firing or from ordinary Portland cement (OPC) concrete, and thus contain high embodied energy and have large carbon footprint. In many areas of the world, there is already a shortage of natural source material for production of the conventional bricks. For environmental protection and sustainable development, extensive research has been conducted on production of bricks from waste materials. This paper presents a state-of-the-art review of research on utilization of waste materials to produce bricks. A wide variety of waste materials have been studied to produce bricks with different methods. The research can be divided into three general categories based on the methods for producing bricks from waste materials: firing, cementing and geopolymerization. Although much research has been conducted, the commercial production of bricks from waste materials is still very limited. The possible reasons are related to the methods for producing bricks from waste materials, the potential contamination from the waste materials used, the absence of relevant standards, and the slow acceptance of waste materials-based bricks by industry and public. For wide production and application of bricks from waste materials, further research and development is needed, not only on the technical, economic and environmental aspects but also on standardization, government policy and public education related to waste recycling and sustainable development. © 2013 Elsevier Ltd. All rights reserved.
• Zhang, L., & Ahmari, S. (2013). Nonlinear analysis of laterally loaded rigid piles in cohesive soil. International Journal for Numerical and Analytical Methods in Geomechanics, 37(2), 201-220.
  More info

  Abstract: This article presents a method for the nonlinear analysis of laterally loaded rigid piles in cohesive soil. The method considers the force and the moment equilibrium to derive the system equations for a rigid pile under a lateral eccentric load. The system equations are then solved using an iteration scheme to obtain the response of the pile. The method considers the nonlinear variation of the ultimate lateral soil resistance with depth and uses a new closed-form expression proposed in this article to determine the lateral bearing factor. The method also considers the horizontal shear resistance at the pile base, and a bilinear relationship between the shear resistance and the displacement is used. For simplicity, the modulus of horizontal subgrade reaction is assumed to be constant with depth, which is applicable to piles in overconsolidated clay. The nonlinearity of the modulus of horizontal subgrade reaction with pile displacement at ground surface is also considered. The validity of the developed method is demonstrated by comparing its results with those of 3D finite element analysis. The applications of the developed method to analyze five field test piles also show good agreement between the predictions and the experimental results. The developed method offers an alternative approach for simple and effective analysis of laterally loaded rigid piles in cohesive soil. © 2011 John Wiley & Sons, Ltd.
• Zhang, L., Chen, J., Zhang, L., & Chen, J. (2013). Effect of Spatial Correlation of Cone Tip Resistance on the Bearing Capacity of Piles. Journal of Geotechnical and Geoenvironmental Engineering, 139(3), 494-500. doi:10.1061/(asce)gt.1943-5606.0000775
• Zhang, Q., Zhu, H., & Zhang, L. (2013). Modification of a generalized three-dimensional Hoek-Brown strength criterion. International Journal of Rock Mechanics and Mining Sciences, 59, 80-96.
  More info

  Abstract: To take account of the influence of the intermediate principle stress, Zhang and Zhu [1,2] proposed a three-dimensional (3D) version of the generalized Hoek-Brown strength criterion. The generalized Zhang-Zhu strength criterion is a true 3D version of the Hoek-Brown criterion, not only inheriting the advantages of the Hoek-Brown strength criterion, but predicts the same strength as the two-dimensional (2D) Hoek-Brown strength criterion at both triaxial compression and extension states. However, the failure surface of the generalized 3D Zhang-Zhu strength criterion is not smooth at either the triaxial compression or extension state and concave at the triaxial extension state, which may have problems with some stress paths and cause inconvenience for numerical applications. In this paper, the reason for the non-smoothness and non-convexity of the generalized 3D Zhang-Zhu strength criterion was first discussed by studying its Lode dependence. Then the criterion was modified by utilizing three different Lode dependences with characteristics of both smoothness and convexity to replace its Lode dependence. Finally the smoothness, convexity and prediction accuracy of the modified criteria were evaluated by applying them to analyze both intact rocks and jointed rock masses. The modified criteria not only keep the advantages of the generalized 3D Zhang-Zhu strength criterion, but solve the non-smoothness and non-convexity problem with no loss of accuracy for strength prediction. © 2012 Elsevier Ltd.
• Zhe, L. i., Chen, R., & Zhang, L. (2013). Utilization of chitosan biopolymer to enhance fly ash-based geopolymer. Journal of Materials Science, 48(22), 7986-7993.
  More info

  Abstract: This paper investigates the enhancement of fly ash-based geopolymer with chitosan biopolymer. Unconfined compression and split tensile tests were carried out to investigate the effect of addition of small amount of N-carboxymethyl chitosan (0.05, 0.1, 0.15, and 0.2 wt% of fly ash) on the mechanical performance of fly ash-based geopolymer. Scanning electron microscopy (SEM) imaging was also conducted to study the microstructure of the chitosan enhanced fly ash-based geopolymer. The results indicated that the inclusion of N-carboxymethyl chitosan led to slight increase of the unconfined compressive strength and substantial increase of the tensile strength, the displacement at the peak tensile load and the pre-peak toughness, with the maximum increases at 0.1 wt% chitosan content. The SEM imaging indicated that the added N-carboxymethyl chitosan biopolymer coated and bridged the (geopolymerized) fly ash particles and led to the formation of a more condensed geopolymer network structure, thus enhancing the mechanical behavior of the geopolymer-biopolymer composite. However, when too much N-carboxymethyl chitosan was used, the excessive coating and encapsulation of un-reacted and partially hydrolyzed fly ash particles hindered their geopolymerization and adversely affected the mechanical behavior of the geopolymer-biopolymer composite. © 2013 Springer Science+Business Media New York.
• Zhu, H., Zhang, Q., & Zhang, L. (2013). Review of research progresses and applications of Hoek-Brown strength criterion. Yanshilixue Yu Gongcheng Xuebao/Chinese Journal of Rock Mechanics and Engineering, 32(10), 1945-1963.
  More info

  Abstract: E. Hoek and E. T. Brown proposed the Hoek-Brown(H-B) strength criterion in 1980. This strength criterion is now widely accepted and studied by researchers and engineers in rock mechanics and engineering field, and is now widely applied to rock mass engineering. In this paper, a systematic review is performed on the progresses of the H-B strength criterion firstly, which are the work by E. Hoek and E. T. Brown, the studies on the three-dimensional H-B strength criteion, the parameters used in this criterion, and the criterion related to anisotropy of rocks with layered joints. Then, the applications of the H-B strength criterion during the past 30 years to different rock mass engineering problems were reviewed. Finally, the progresses of the H-B strength criterion carried out by the authors are introduced. A generalized three-dimensional H-B strength criterion has been proposed and modified by utilizing three different Lode dependences, so it can be directly applied to construct constitutive model and be embedded in numerical software. Based on three-dimensional numerical simulations with particle flow model, the parameters of rock and rock mass used in H-B strength criterion are studied in microscopic scale and a multi-scale relationship is found for providing a more reliable basis for determination of these parameters.
• Ahmari, S., & Zhang, L. (2012). Production of eco-friendly bricks from copper mine tailings through geopolymerization. Construction and Building Materials, 29, 323-331.
  More info

  Abstract: This paper studies the feasibility of utilizing copper mine tailings for production of eco-friendly bricks based on the geopolymerization technology. The procedure for producing the bricks simply includes mixing the tailings with an alkaline solution, forming the brick by compressing the mixture within a mold under a specified pressure, and curing the brick at a slightly elevated temperature. Unlike the conventional method for producing bricks, the new procedure neither uses clay and shale nor requires high temperature kiln firing, having significant environmental and ecological benefits. In this study, the effects of four major factors, sodium hydroxide (NaOH) solution concentration (10 and 15 M), water content (8-18%), forming pressure (0-35 MPa), and curing temperature (60-120 °C), on the physical and mechanical properties of copper mine tailings-based geopolymer bricks are investigated using water absorption and unconfined compression tests. Scanning electron microscopy (SEM) imaging and X-ray diffraction (XRD) analysis are also performed to investigate the microstructure and phase composition of the mine tailings-based geopolymer bricks prepared at different conditions. The results show that copper mine tailings can be used to produce eco-friendly bricks based on the geopolymerization technology to meet the ASTM requirements. © 2011 Elsevier Ltd. All rights reserved.
• Ahmari, S., Ren, X., Toufigh, V., & Zhang, L. (2012). Production of geopolymeric binder from blended waste concrete powder and fly ash. Construction and Building Materials, 35, 718-729.
  More info

  Abstract: Recycling and utilization of waste concrete is a significant contribution to environment and sustainable development. In current practice, the recycling of waste concrete is mainly limited to the use of crushed aggregates in low-specification applications. Few researchers have investigated complete recycling of waste concrete. These complete recycling methods, however, need to re-clinker the hydrated cement using the standard cement kiln procedures and thus consume significant amount of energy and release large quantity of CO 2. To completely recycle and utilize waste concrete in a sustainable and environmentally-friendly way, a method that does not need re-clinkering at high temperature should be used. This paper studies the production of geopolymeric binder from ground waste concrete (GWC) powder mixed with class F fly ash (FA), which can then be used with recycled concrete aggregates to produce new concrete. Specifically, the effect of composition and concentration of the alkaline solution and the content of GWC on the unconfined compressive strength (UCS) of the produced geopolymeric binder is investigated. SEM/EDX, XRD, and FTIR analyses are also performed to investigate the micro/nano-structure, morphology and phase/surface elemental compositions of the produced geopolymeric binder and the effect of calcium (Ca) on them. The results indicate that utilization of GWC together with FA can increase the UCS of the geopolymeric binder up to 50% GWC content. Further increase of GWC decreases the UCS of the geopolymeric binder. So with proper combination of GWC and FA, the geopolymeric binder with required strength can be produced. © 2012 Elsevier Ltd. All rights reserved.
• Ahmari, S., Zhang, L., & Zhang, J. (2012). Effects of activator type/concentration and curing temperature on alkali-activated binder based on copper mine tailings. Journal of Materials Science, 47(16), 5933-5945.
  More info

  Abstract: This article investigates the effects of activator type/concentration and curing temperature on alkaliactivated binder based on copper mine tailings (MT). Different alkaline activators including sodium hydroxide (NaOH), sodium silicate (SS), and sodium aluminate (SA) at different compositions and concentrations were used and four different curing temperatures, 60, 75, 90, and 120 °C, were considered. Scanning electron microscopy/energydispersive X-ray spectroscopy (SEM/EDX), and X-ray diffraction (XRD) were conducted to investigate the effect of these factors on the unconfined compressive strength (UCS), microstructure, and phase composition of the binder. The results indicate that NaOH concentration and curing temperature are two important factors that affect the UCS and micro-structural properties of the alkali-activated MT binder. The optimum curing temperature, i.e., the curing temperature at the maximum UCS, depends on the NaOH concentration, lower optimum curing temperature at smaller NaOH concentration. Addition of aqueous SS to the NaOH solution can lead to strength improvement, with the highest UCS obtained at a SiO2/Na2O ratio of 1.0-1.26. Addition of powder SA to the NaOH solution profoundly delays the setting at 60 °C but improves the UCS at 90 °C. The SEM/EDX results show highly heterogeneous microstructure for the alkali-activated MT binder as evidenced by the variable Si/Al ratios in different phases. The XRD patterns indicate a newly formed crystalline phase, zeolite, in the 90 °C-cured specimens. The results of this study provide useful information for recycling and utilization of copper MT as construction material through the geopolymerization technology. © Springer Science+Business Media, LLC 2012.
• Zhang, L. (2012). Complete recycling and utilization of waste concrete through geopolymerization. C\&D World, 5(3), 30--34.
• Zhang, L. (2012). Underground Compressed Air Energy Storage (CAES). Geo-Strata—Geo Institute of ASCE, 16(1), 34--36.
• Zhang, L., & Chen, J. (2012). Effect of spatial correlation of standard penetration test (SPT) data on bearing capacity of driven piles in sand. Canadian Geotechnical Journal, 49(4), 394-402.
  More info

  Abstract: In this paper, the effect of spatial correlation of standard penetration test (SPT) data on the bearing capacity of driven piles in sand is analyzed. First, the direct approach for using SPT data to determine the bearing capacity of piles in sand is used to derive the expressions for probabilistic prediction of pile bearing capacity by considering the spatial correlation of the SPT data. To analyze the relationship between the probability of failure and the factor of safety, a procedure based on the advanced first-order, second-moment (FOSM) method is used. Then parametric studies are conducted on the spatial correlation between the spatial average of SPT numbers over the pile length, NLV, and the spatial average of SPT numbers over an interval near the pile base, NbV, and its effect on the bearing capacity of piles. The results indicate that it is important to consider the spatial correlation between NLV and NbV in the probabilistic prediction of pile bearing capacity. Ignoring this spatial correlation will underestimate the probability of failure and lead to unsafe design. Finally, three tested piles are analyzed to demonstrate the probabilistic analysis of piles by considering the spatial correlation of SPT data and the procedure for probabilistic analysis of pile bearing capacity is summarized.
• Zhang, L., & Chen, J. (2012). Effect of spatial correlation of standard penetration test (SPT) data on bearing capacity of driven piles in sand. Canadian Geotechnical Journal, 49(4), 394-402. doi:10.1139/t2012-005
• Zhang, L., Ding, X., & Budhu, M. (2012). A rock expert system for the evaluation of rock properties. International Journal of Rock Mechanics and Mining Sciences, 50, 124-132.
• Zhang, L. (2011). Reply to the discussion by ArIoglu et al. on "estimating the strength of jointed rock Masses" by Zhang, DOI 10.1007/s00603-009-0065-x. Rock Mechanics and Rock Engineering, 44(4), 511-.
• Zhang, L., & Ahmari, S. (2011). Nonlinear analysis of laterally loaded rigid piles in cohesive soil: ANALYSIS OF LATERALLY LOADED RIGID PILES IN COHESIVE SOIL. International Journal for Numerical and Analytical Methods in Geomechanics, 37(2), 201-220. doi:10.1002/nag.1094
• Zhang, L., Ahmari, S., & Zhang, J. (2011). Synthesis and characterization of fly ash modified mine tailings-based geopolymers. Construction and Building Materials, 25(9), 3773-3781.
  More info

  Abstract: Each year, the mining industry generates a significant amount of mine tailings. Storage of these tailings occupies large areas of land and leads to high monetary, environmental and ecological costs. In this research, a feasibility study is performed on geopolymerization of mine tailings so that they can be recycled and utilized as construction material. Considering the extremely high silicon to aluminum (Si/Al) ratio for the mine tailings, class F fly ash is used to adjust the Si/Al ratio. Sodium hydroxide (NaOH) solution is used as the alkaline reaction agent. The research consists of unconfined compression tests to evaluate the mechanical properties, scanning electron microscopy (SEM) imaging to investigate the microstructure, and the X-ray diffraction (XRD) analysis to study the phase compositions. The effects of fly ash content (which affects the Si/Al ratio), alkalinity (NaOH concentration), and curing time on the geopolymerization of mine tailings are studied in a systematic way. The results show that the Si/Al ratio and the alkalinity have profound effects on the mechanical and micro-structural properties of the mine tailings-based geopolymers. The curing time affects the mechanical and micro-structural properties of the mine tailings-based geopolymers mainly during the first 7 days. Based on the research, it can be concluded that mine tailings are a viable and promising construction material if the geopolymerization technology is utilized. © 2011 Elsevier Ltd. All rights reserved.
• Zhang, Q., Zhu, H., Zhang, L., & Ding, X. (2011). Study of scale effect on intact rock strength using particle flow modeling. International Journal of Rock Mechanics and Mining Sciences, 48(8), 1320-1328.
  More info

  Abstract: Based on the extensive review of the UCS versus specimen size test data and the various empirical relations between the UCS and the specimen size, a new expression is proposed to describe the dependence of the UCS on specimen volume. The proposed new relation can fit the UCS versus specimen size test data of different rocks very well. Then, a numerical study of the scale effect on UCS is conducted using a numerical model in which the intact rock is represented by particles bonded to each other at contact points, with the contact bonds having both normal and shear strength components. The bond can break if the normal or shear contact stress exceeds the corresponding bond strength. To simulate the initial micro-fractures (flaws or cracks) in the rock, the smooth-joint contact model is used. The fractures are considered to be randomly orientated and located disks. The size and number of fractures are described by an exponential expression derived using fractal theory. The numerical model is calibrated using the test stress-strain curves of 80. mm×40. mm×40. mm prism Yamaguchi marble samples. Then, the calibrated model is used to predict the UCS of Yamaguchi marble samples at different sizes. The predicted UCS values are in good agreement with the experimental values. The numerical simulations show that to capture the scale effect on UCS of intact rock, initial fractures with sizes increasing faster with the specimen size must be considered in the modeling. © 2011 Elsevier Ltd.
• Zhang, L. (2010). A simple method for evaluating liquefaction potential from shear wave velocity. Frontiers of Architecture and Civil Engineering in China, 4(2), 178-195.
  More info

  Abstract: The simplified procedure using shear wave velocity measurements is increasingly used to evaluate the seismic liquefaction potential of soils. This procedure is based on finding the boundary separating the liquefaction and non-liquefaction cases through the analysis of liquefaction case histories, following the general format of the Seed-Idriss simplified procedure based on standard penetration test (SPT) data. It is noted that many assumptions have been made in the simplified procedure. This paper develops a simple method for evaluating the liquefaction potential of soils from shear wave velocity by using the optimum seeking method to directly analyze the liquefaction history data and quantify the influence of major factors affecting the liquefactions potential of soils. The factors considered are the earthquake magnitude, the vertical effective overburden stress, the shear wave velocity, the peak acceleration at the ground surface of the site, and the fines content of the soil. The most important factor has been identified as the shear wave velocity. The developed method uses the measured data directly and in a very simple way. Neither stress-correction of shear wave velocity nor calculation of cyclic shear stress as in the simplified procedure is required. Comparisons indicate that the developed simple method has a higher success rate for evaluating liquefaction potential of soils than the simplified procedure. A case study is presented to illustrate the application of the developed simple method and further confirms its accuracy. © 2010 Higher Education Press and Springer-Verlag Berlin Heidelberg.
• Zhang, L. (2010). Estimating the strength of jointed rock masses. Rock Mechanics and Rock Engineering, 43(4), 391-402.
  More info

  Abstract: Determination of the strength of jointed rock masses is an important and challenging task in rock mechanics and rock engineering. In this article, the existing empirical methods for estimating the unconfined compressive strength of jointed rock masses are reviewed and evaluated, including the jointing index methods, the joint factor methods, and the methods based on rock mass classification. The review shows that different empirical methods may produce very different estimates. Since in many cases, rock quality designation (RQD) is the only information available for describing rock discontinuities, a new empirical relation is developed for estimating rock mass strength based on RQD. The newly developed empirical relation is applied to estimate the unconfined compressive strength of rock masses at six sites and the results are compared with those from the empirical methods based on rock mass classification. The estimated unconfined compressive strength values from the new empirical relation are essentially in the middle of the estimated values from the different empirical methods based on rock mass classification. Similar to the existing empirical methods, the newly developed relation is only approximate and should be used, with care, only for a first estimate of the unconfined compressive strength of rock masses. Recommendations are provided on how to apply the newly developed relation in combination with the existing empirical methods for estimating rock mass strength in practice. © Springer-Verlag 2009.
• Zhang, L. (2010). Method for Estimating the Deformability of Heavily Jointed Rock Masses. Journal of Geotechnical and Geoenvironmental Engineering, 136(9), 1242-1250. doi:10.1061/(asce)gt.1943-5606.0000344
• Zhang, L. (2010). Method for estimating the deformability of heavily jointed rock masses. Journal of Geotechnical and Geoenvironmental Engineering, 136(9), 1242-1250.
  More info

  Abstract: Determination of the deformability of jointed rock masses is an important and challenging task in rock mechanics and rock engineering. In this paper, simple expressions are derived for estimating the equivalent isotropic deformation properties of heavily jointed rock masses using the methodology of equivalent continuum approach. The derived expressions are compared with two analytical relations in the literature and the field test data relating rock quality designation (RQD) and deformation modulus ratio Em/Er, where Em and Er are the deformation modulus of the rock mass and the intact rock, respectively. The derived expressions are in reasonable agreement with the existing analytical relations in the literature and satisfactorily predict the range of the field RQD versus modulus ratio Em/Er data. Finally two examples are presented to demonstrate the application of the derived expressions by applying them to estimate the deformation modulus of jointed rock mass at two sites. The results of the paper can be of help in predicting the deformation behavior of jointed rock masses when the properties of the intact rock and discontinuities are available. © 2010 ASCE.
• Zhang, L. (2010). Nonlinear Analysis of Torsionally Loaded Piles in a Two-Layer Soil Profile. International Journal of Geomechanics, 10(2), 65-73. doi:10.1061/(asce)gm.1943-5622.0000038
• Zhang, L. (2010). Nonlinear analysis of torsionally loaded piles in a two-layer soil profile. International Journal of Geomechanics, 10(2), 65-73.
  More info

  Abstract: This paper presents a method for predicting the nonlinear response of torsionally loaded piles in a two-layer soil profile, such as a clay or sand layer underlain by rock. The shear modulus of the upper soil is assumed to vary linearly with depth and the shear modulus of the lower soil is assumed to vary linearly with depth and then stay constant below the pile tip. The method uses the variational principle to derive the governing differential equations of a pile in a two-layer continuum and the elastic response of the pile is then determined by solving the derived differential equations. To consider the effect of soil yielding on the behavior of piles, the soil is assumed to behave linearly elastically at small strain levels and yield when the shear stress on the pile-soil interface exceeds the corresponding maximum shear resistance. To determine the maximum pile-soil interface shear resistance, methods that are available in the literature can be used. The proposed method is verified by comparing its results with existing elastic solutions and published small-scale model pile test results. Finally, the proposed method is used to analyze two full-scale field test piles and the predictions are in reasonable agreement with the measurements. © 2010 ASCE.
• Zhang, L. (2010). Prediction of end-bearing capacity of rock-socketed shafts considering rock quality designation (RQD). Canadian Geotechnical Journal, 47(10), 1071-1084. doi:10.1139/t10-016
• Zhang, L. (2010). Prediction of end-bearing capacity of rocksocketed shafts considering rock quality designation (RQD). Canadian Geotechnical Journal, 47(10), 1071-1084.
  More info

  Abstract: Existing empirical methods for determining the end-bearing capacity, qmax, use empirical relations between qmax and the unconfined compressive strength of intact rock, sc. As rock-socketed shafts are supported by the rock mass, not just the intact rock, one should consider not only the intact rock properties, but also the influence of discontinuities on rock mass properties when determining qmax. Although semi-empirical and analytical methods have been developed that can consider the effect of discontinuities, they are more complicated than the empirical relations and require information about discontinuities that is often not available or difficult to obtain in engineering practice. In this paper, an empirical relation between qmax and the unconfined compressive strength of rock mass, σcm, is developed. The new empirical relation explicitly considers the effect of discontinuities represented by rock quality designation (RQD), which is the parameter normally obtained in engineering practice. The accuracy of the expression for estimating scm based on RQD is verified by comparing its estimation values with those from the existing empirical expressions based on rock mass classification. Two examples are presented to show the application of the newly developed empirical relation between qmax and σcm.
• Zhang, L., & Ding, X. (2010). Variance of non-parametric rock fracture mean trace length estimator. International Journal of Rock Mechanics and Mining Sciences, 47(7), 1222-1228.
• Zhang, L., & Einstein, H. H. (2010). The planar shape of rock joints. Rock Mechanics and Rock Engineering, 43(1), 55-68.
  More info

  Abstract: Knowing the planar shape of discontinuities is important when characterizing discontinuities in a rock mass. However, the real discontinuity shape is rarely known, since the rock mass is usually inaccessible in three dimensions. Information on discontinuity shape is limited and often open to more than one interpretation. This paper discusses the planar shape of rock joints, the most common discontinuities in rock. First, a brief literature review about the shape of joints is presented, including some information on joint-surface morphology, inferences from observed trace lengths on different sampling planes, information based on experimental studies, and joint shapes assumed by different researchers. This review shows that joints not affected by adjacent geological structures such as bedding boundaries or pre-existing fractures tend to be elliptical (or approximately circular but rarely). Joints affected by or intersecting such geological structures tend to be rectangular. Then, using the general stereological relationship between trace length distributions and joint size distributions developed by Zhang et al. (Geotechnique 52(6):419-433, 2002) for elliptical joints, the effect of sampling plane orientation on trace lengths is investigated. This study explains why the average trace lengths of non-equidimensional (elliptical or similar polygonal) joints on two sampling planes can be about equal and thus the conclusion that rock joints are equidimensional (circular) drawn from the fact that the average trace lengths on two sampling planes are approximately equal can be wrong. Finally, methods for characterizing the shape and size of joints (elliptical or rectangular) from trace length data are recommended, and the appropriateness of using elliptical joint shapes to represent polygonal, especially rectangular, joints is discussed. © 2009 Springer-Verlag.
• Zhang, L., Cao, P., & Radha, K. C. (2010). Evaluation of rock strength criteria for wellbore stability analysis. International Journal of Rock Mechanics and Mining Sciences, 47(8), 1304-1316.
  More info

  Abstract: Polyaxial strength test data of five rocks are used to examine the Mohr-Coulomb, Drucker-Prager, modified Lade, Mogi-Coulomb and three-dimensional (3D) Hoek-Brown criteria regarding their ability, with parameters determined based on the triaxial compression test data, to represent the rock behavior under polyaxial stress states. Then the five strength criteria, with parameters determined based on the triaxial compression test data, are used to analyze wellbore stability of both vertical and inclined boreholes. The results show that the Mohr-Coulomb criterion under-predicts the polyaxial strength and estimates the highest minimum mud pressure required for wellbore stability while the Drucker-Prager criterion over-predicts the polyaxial strength and estimates the lowest minimum mud pressure. The modified Lade, Mogi-Coulomb and 3D Hoek-Brown criteria, with parameters based on triaxial test data, can either over-predict or under-predict the polyaxial strength. The over-prediction of the modified Lade criterion can be very large, and thus it may be unsafe to use it to estimate the minimum mud pressure. Both the over-prediction and under-prediction are relatively small for the 3D Hoek-Brown and Mogi-Coulomb criteria. Therefore, the 3D Hoek-Brown and Mogi-Coulomb criteria are recommended for wellbore stability analysis. © 2010 Elsevier Ltd.
• Einstein, H. H., & Zhang, L. (2009). The importance of discontinuities. Geo-Strata, 18-21.
• Zhang, L. (2009). Nonlinear analysis of laterally loaded rigid piles in cohesionless soil. Computers and Geotechnics, 36(5), 718-724.
  More info

  Abstract: In this paper, a method is developed for nonlinear analysis of laterally loaded rigid piles in cohesionless soil. The method assumes that both the ultimate soil resistance and the modulus of horizontal subgrade reaction increase linearly with depth. By considering the force and moment equilibrium, the system equations are derived for a rigid pile under a lateral eccentric load. An iteration scheme containing three main steps is then proposed to solve the system equations to obtain the response of the pile. To determine the ultimate soil resistance and the modulus of horizontal subgrade reaction required in the analysis, related expressions are selected by reviewing and assessing the existing methods. The degradation of the modulus of horizontal subgrade reaction with pile displacement at ground surface is also considered. The developed method is validated by comparing its results with those of centrifugal tests and three-dimensional finite element analysis. Applications of the developed method to laboratory model and field test piles also show good agreement between the predictions and the experimental results. © 2008 Elsevier Ltd. All rights reserved.
• Zhang, L. (2008). A generalized three-dimensional Hoek-Brown strength criterion. Rock Mechanics and Rock Engineering, 41(6), 893-915.
  More info

  Abstract: Although the Hoek-Brown strength criterion has been widely used in rock mechanics and rock engineering, it does not take account of the influence of the intermediate principal stress. Much evidence, however, has been accumulating to indicate that the intermediate principal stress does influence the rock strength in many instances. Therefore, researchers have developed three-dimensional (3D) versions of the Hoek-Brown strength criterion. In this paper, three existing 3D versions of the Hoek-Brown strength criterion are reviewed and evaluated. The evaluation shows that all of the three 3D versions of the Hoek-Brown strength criterion have limitations. To address the limitations, a generalized 3D Hoek-Brown criterion is proposed by modifying the generalized Hoek-Brown strength criterion. The proposed 3D criterion not only inherits the advantages of the Hoek-Brown strength criterion but can take account of the influence of the intermediate principal stress. At a 2D stress state (triaxial or biaxial), the proposed 3D criterion will simply reduce to the form of the generalized Hoek-Brown strength criterion. To validate the proposed 3D strength criterion, polyaxial or true triaxial compression test data of intact rocks and jointed rock masses has been collected from the published literature. Predictions of the proposed generalized 3D Hoek-Brown strength criterion are in good agreement with the test data for a range of different rock types. The difference of the proposed generalized 3D Hoek-Brown strength criterion from and its advantages over the existing 3D versions of the Hoek-Brown strength criterion are also discussed. It should be noted that the proposed 3D criterion is empirical in nature because it is an extension of the 2D Hoek-Brown strength criterion, which is empirical. Because of the non-convexity of the yield surface for a biaxial stress state, the proposed 3D criterion may have problems with some stress paths. © 2008 Springer-Verlag.
• Zhang, L., & Zhu, H. (2007). Three-Dimensional Hoek-Brown Strength Criterion for Rocks. Journal of Geotechnical and Geoenvironmental Engineering, 133(9), 1128-1135. doi:10.1061/(asce)1090-0241(2007)133:9(1128)
• Zhang, L., & Zhu, H. (2007). Three-dimensional hoek-brown strength criterion for rocks. Journal of Geotechnical and Geoenvironmental Engineering, 133(9), 1128-1135.
  More info

  Abstract: A great number of rock strength criteria have been proposed over the past decades. Of these different strength criteria, the Hoek-Brown strength criterion has been used most widely, because: (1) it has been developed specifically for rock materials and rock masses; (2) its input parameters can be determined from routine unconfined compression tests, mineralogical examination, and discontinuity characterization; and (3) it has been applied for over 20 years by practitioners in rock engineering, and has been applied successfully to a wide range of intact and fractured rock types. The Hoek-Brown strength criterion, however, does not take account of the influence of the intermediate principal stress, although much evidence has been accumulating to indicate that the intermediate principal stress does influence the rock strength in many instances. In this paper, a three-dimensional (3D) version of the Hoek-Brown strength criterion has been proposed. The original Hoek-Brown strength criterion is just a two-dimensional (2D) version of the proposed 3D strength criterion. The 3D strength criterion not only inherits the advantages of the original Hoek-Brown strength criterion, but can take account of the influence of the intermediate principal stress. Polyaxial or true triaxial compression test data of intact rocks and jointed rock masses has been collected from the published literature and used to validate the proposed 3D Hoek-Brown strength criterion. Predictions of the proposed 3D Hoek-Brown strength criterion are in good agreement with the test data for a range of different rock types. The proposed 3D Hoek-Brown strength criterion is also compared with a simplified 3D Hoek-Brown strength criterion proposed by Pan and Hudson. The Pan-Hudson criterion cannot be considered a true 3D version of the Hoek-Brown criterion, because it does not reduce to the form of the original Hoek-Brown criterion at either triaxial or biaxial state. The Pan-Hudson criterion underpredicts the strength at the triaxial state, but overpredicts the strength at the biaxial state. © 2007 ASCE.
• Zhang, L. (2006). Preface. Elsevier Geo-Engineering Book Series, 4(C), vii-viii.
• Zhang, L., Silva, F., & Grismala, R. (2006). Closure to "Ultimate lateral resistance to piles in cohesionless soils" by Lianyang Zhang, Francisco Silva, and Ralph Grismala. Journal of Geotechnical and Geoenvironmental Engineering, 132(8), 1109-1110.
• Zhang, L., Silva, F., & Grismala, R. (2005). Ultimate lateral resistance to piles in cohesionless soils. Journal of Geotechnical and Geoenvironmental Engineering, 131(1), 78-83.
  More info

  Abstract: Several methods are available for predicting the ultimate lateral resistance to piles in cohesionless soils. However, these methods often produce significantly different ultimate resistance values. This makes it difficult for practicing engineers to effectively select the appropriate method when designing laterally loaded piles in cohesionless soils. By analyzing the lateral soil resistance distribution along the width of the pile and based on the test results of model rigid piles in cohesionless soils collected from the published literature, a simple method is proposed for calculating the ultimate lateral resistance (including frontal soil resistance and side shear resistance) to piles in cohesionless soils. The calculated ultimate lateral resistance from the proposed method agrees well with that obtained from centrifugal tests of flexible model piles. Predicting the lateral load capacity of laboratory and field rigid test piles in cohesionless soils using the proposed method also yields satisfactory results. © ASCE.
• Zhang, L., & Einstein, H. H. (2004). Using RQD to estimate the deformation modulus of rock masses. International Journal of Rock Mechanics and Mining Sciences, 41(2), 337-341.
• Zhang, L., Einstein, H. H., & Dershowitz, W. S. (2002). Stereological relationship between trace length and size distribution of elliptical discontinuities. Geotechnique, 52(6), 419-433.
  More info

  Abstract: This paper presents an approach for estimating the size distributions of elliptical discontinuities. This is an extension of approaches for estimating size distributions of circular discontinuities. By assuming an elliptical shape and changing the aspect ratio k of the ellipses (i.e. the ratio of the major to minor axes), many real discontinuities can be reasonably represented. For elliptical discontinuities, a general stereological relationship between distributions of trace length and distributions of discontinuity size (expressed by the major axis length, a, of the ellipse) is derived for area (or window) sampling. From this relationship, expressions are derived between the mean (μa) and standard deviation (σa) of the discontinuity size, a, and the mean (μl) and standard deviation (σl) of the trace length, l, respectively for log-normal, negative exponential and gamma distributions of discontinuity sizes. Using the derived expressions, the effect of sampling plane orientation on trace lengths is investigated. The results show that the sampling plane orientation has an important effect on both the mean and the standard deviation of trace lengths. Finally, the derived stereological relationship between the trace length distribution and the discontinuity size distribution was used in a simulation with the FracMan discrete fracture code. The results show that the approach for inferring the major axis orientation, aspect ratio and size distribution of discontinuities from observations on outcrops is satisfactory.
• Zhang, L., & Einstein, H. H. (2000). Estimating the intensity of rock discontinuities. International Journal of Rock Mechanics and Mining Sciences, 37(5), 819-837.
  More info

  Abstract: This paper presents an approach for estimating the intensity of discontinuities and formulating intensity and orientation as a fracture tensor. Specifically the size distribution and the number of discontinuities are estimated first, from which the fracture tensor is then derived. Discontinuity size distribution is inferred from the trace data sampled in circular windows by using a general stereological relationship between the true trace length distribution and the discontinuity diameter distribution assuming circular shaped discontinuities. Because the measured trace lengths are biased, a method is proposed to estimate the true trace length distribution for circular window sampling. Circular window sampling has the advantage of automatically eliminating the orientation bias when estimating the true trace lengths. A method is then presented with which the total number of discontinuities in an objective volume can be estimated from the number of discontinuities observed in normal-size boreholes and using the inferred discontinuity diameter from the circular window sampling on the rock surface. With the derived size distribution and number of discontinuities, the intensity of discontinuities, which is the total surface area of discontinuities per unit volume, can then be calculated and included in a new definition of a fracture tensor. An application of the approach to analyze simulated discontinuities produces satisfactory results. (C) 2000 Elsevier Science Ltd. All rights reserved.
• Zhang, L., Ernst, H., & Einstein, H. H. (2000). Nonlinear analysis of laterally loaded rock-socketed shafts. Journal of Geotechnical and Geoenvironmental Engineering, 126(11), 955-968.
  More info

  Abstract: In this paper, a nonlinear continuum method is developed to predict the load-displacement response of drilled shafts under lateral loading. The method can consider drilled shafts in a continuum consisting of a soil layer overlying a rock mass layer. The deformation modulus of the soil is assumed to vary linearly with depth, and the deformation modulus of the rock mass is assumed to vary linearly with depth and then to stay constant below the shaft tip. The effect of soil and/or rock mass yielding on the behavior of shafts is considered by assuming that the soil and/or rock mass behaves linearly elastically at small strain levels and yields when the soil and/or rock mass reaction force p (force/length) exceeds the ultimate resistance p(ult) (force/length). For the calculation of the ultimate resistance p(ult) of the soil, methods that are available in the literature are used. To calculate the ultimate resistance p(ult) of the rock mass, a method based on the Hoek-Brown strength criterion is proposed. The proposed method is verified by comparing its results with available elastic solutions and field test data, and it is finally applied in the design of a bridge foundation in Massachusetts.
• Zhang, L. (1999). Closure to “Assessment of Liquefaction Potential Using Optimum Seeking Method” by Lianyang Zhang. Journal of Geotechnical and Geoenvironmental Engineering, 125(12), 1105--1106.
• Zhang, L., & Einstein, H. H. (1999). Closure to “End Bearing Capacity of Drilled Shafts in Rock” by Lianyang Zhang and Herbert H. Einstein. Journal of Geotechnical and Geoenvironmental Engineering, 125(12), 1109--1110.
• Zhang, L. (1998). Assessment of liquefaction potential using optimum seeking method. Journal of Geotechnical and Geoenvironmental Engineering, 124(8), 739-748.
  More info

  Abstract: The use of the cone pentration test (CPT) resistance data as an index for liquefaction assessments is receiving increased attention because of the advantages of this in-situ test method. This paper investigates the feasibility of using the optimum seeking method to assess liquefaction potential from actual CPT field data. Optimization theory is a very important branch of applied mathematics, and has a wide application in the practical world. Using the available field liquefaction and nonliquefaction data, the influence of various factors is quantified using the optimum seeking method. The factors considered are: the earthquake magnitude, M; the vertical effective overburden stress, σ'vO; the CPT tip resistance, c; the peak acceleration at the ground surface of the site, amax; and the median grain diameter of the soil, D50. The most important factor has been identified as the CPT tip resistance. Since neither normalization of qc nor calculation of seismic shear stress is required, the proposed method is simpler than the conventional method of evaluating liquefaction potential. Comparisons indicate that the proposed method gives a rate of success for evaluating liquefaction potential equivalent to or somehwat higher than that by the conventional method.
• Zhang, L. (1998). Predicting seismic liquefaction potential of sands by optimum seeking method. Soil Dynamics and Earthquake Engineering, 17(4), 219-226.
  More info

  Abstract: The feasibility of using the optimum seeking method to assess the seismic liquefaction potential of sands has been investigated. Optimization theory is a very important branch of applied mathematics and has a wide application in the practical world. Using the available field sand liquefaction data, the influence of various factors is quantified using the optimum seeking method. The factors considered are: the earthquake magnitude M, the distance of the site from the source of the earthquake L, the depth of the water table Dw, the depth of the sand deposit Ds, and the standard penetration test (SPT) blow count N. The most important factors have been identified as the earthquake magnitude and the SPT blow count. Prediction results show that the proposed method is effective and feasible. Since neither normalization of the SPT blow count nor calculation of the seismic shear-stress ratio are required, the proposed method is simpler and more direct than the conventional methods of evaluating liquefaction potential. © 1998 Elsevier Science Ltd. All rights reserved.
• Zhang, L., & Einstein, H. H. (1998). End bearing capacity of drilled shafts in rock. Journal of Geotechnical and Geoenvironmental Engineering, 124(7), 574-584.
• Zhang, L., & Einstein, H. H. (1998). Estimating the mean trace length of rock discontinuities. Rock Mechanics and Rock Engineering, 31(4), 217-235.
  More info

  Abstract: Rock discontinuities appear as traces on exposures such as natural outcrops or tunnel walls. Discontinuity size which has important effects on rock mass behavior is related to trace length. This paper presents a technique for estimating mean trace length from the observations made on finite, circular sampling windows. The method takes sampling errors into account and it requires, like existing methods using rectangular sampling windows, that the numbers of discontinuities with both ends censored, with one end observed and one end censored, and with both ends observed be known. Knowledge of the lengths of the observed traces and the distribution of trace lengths is not required. A major advantage of the proposed method over the existing methods is that it does not need sampling data about the orientation of discontinuities, i.e. the proposed method is applicable to traces with arbitrary orientation distributions. To check the validity of the proposed method, theoretical relations between the mean trace length and the mean diameter of circular discontinuities, respectively for lognormal and negative exponential distributions of the diameter of discontinuities, are derived. The proposed method is then applied to analyze data simulated with the FracMan code, and the predicted results are compared to the corresponding theoretical solutions. The results show that the proposed method is satisfactory. Comparisons of the predicted mean trace length with the mean of observed trace lengths show that it is important to consider sampling biases when estimating mean trace length.

Proceedings Publications

• Nikvar-Hassani, A. .., & Zhang, L. (2023, 2023). A novel hybrid cementitious material for pumpable roof supports: From laboratory-scale investigation to full-scale production. In 42nd International Conference on Ground Control in Mining, July 25 - 27, 2023, Canosburg, PA, 9.
• Zhang, L. (2023, 2023). Utilization of mine wastes as road construction material through geopolymerization. In IRF R2T Conference & Exhibition, November 14 - 17, 2023, Phoenix, AZ,, 12.
• Zhang, L., & Chen, H. (2023, 2023). A Simple App for Rapid and Refined Analysis of Open Pit Rock Slope Stability. In SME MINEXCHANGE 2023 Annual Conference & Expo, February 26 - March 1, 2023, Denver, CO, 6.
• Amjad, U. (2022, 2022). Real-time structural health monitoring of concrete using the non-linear ultrasonic SPC-I technique. In Proceedings of ASME 2022 49th Annual Review of Progress in Quantitative Nondestructive Evaluation: QNDE2022, Paper-98407.
• Deng, J. (2022, 2022). Effect of pulse shape and duration on induced pillar rockbursts. In RaSiM10: Rockbursts and Seismicity in Mines, Paper-2203.
• Chen, H., Zhu, H., & Zhang, L. (2020, 2020). A Strain Softening/Hardening Constitutive Model for Rock Based on Newly Modified GZZ Criterion. In 54th US Rock Mechanics/Geomechanics Symposium.
• Nikvar-Hassani, A., & Zhang, L. (2020, 2020). Development of a New Geopolymer Based Cementitious Material for Pumpable Roof Supports in Underground Mining. In Geo-Congress 2020: Engineering, Monitoring, and Management of Geotechnical Infrastructure, 325-334.
• Manjarrez, L., & Zhang, L. (2019, November). Using DEM to study the behavior of granular soils under cyclic shear loading. In Geotechnical Engineering in the XXI Century: Lessons Learned and Future Challenges, Proceedings of XVI Pan-American Conference on Soil Mechanics and Geotechnical Engineering (XVI PCSMGE), 611-619.
• An, M., Zhang, F., Zhang, L., & Yang, F. (2018, May). Effects of normal stress and clay content on the frictional properties of reservoir rocks under fully saturated conditions. In Proceedings of GeoShanghai 2018 International Conference: Rock Mechanics and Rock Engineering, 228-239.
• Hu, J., & Zhang, L. (2018, May). Prediction of long-term settlements of foundations supporting high and heavy storage tanks based on short-term field measurements. In Proceedings of GeoShanghai 2018 International Conference: Advances in Soil Dynamics and Foundation Engineering, 654-661.
• Hu, J., Wu, X., & Zhang, L. (2018, May). Reevaluation of soil compression properties for an aluminum refinery plant. In Proceedings of GeoShanghai 2018 International Conference: Fundamentals of Soil Behaviors, 354-361.
• Wang, X., Zhu, H., & Zhang, L. (2018, October). A three-dimensional damage-softening statistical constitutive model for rock based on GZZ criterion. In 10th Asian Rock Mechanics Symposium and The ISRM International Symposium for 2018, 10.
• Yin, Z., Zhang, F., Chen, Z., Zhang, L., & Maxwell, S. (2018, Number). Geomechanical modeling of fault reactivation and induced seismicity by the flowback of hydraulic fracturing fluid. In CouFrac - International Conference on Coupled Processes in Fractured Geological Media: Observation, Modeling, and Application, 4.
• Zhang, F., Yin, Z., Chen, Z., Maxwell, S., Zhang, L., & Wu, Y. (2018, August). Fault reactivation and induced seismicity during multi-stage hydraulic fracturing: field microseismic analysis and geomechanical modeling. In International Conference on Applied Energy, 6.
• An, M., Zhang, F., & Zhang, L. (2017, August). Experimental investigation of frictional healing and frictional creep behavior of typical reservoir rocks in China. In The Chinese Congress of Theoretical and Applied Mechanics (CCTAM-2017), 14.
• Ren, X., & Zhang, L. (2016). The Complete Recycling of Waste Concrete to Produce Geopolymer Concrete. In Geo-Chicago 2016, 103--111.
• Zhang, L. (2016, June). Characterization of rock masses using rock quality designation (RQD). In Transportation Research Congress (TRC) 2016, 6.
• Ding, X., Zhang, L., & others, . (2015). Numerical Study of Cracking Process using a new Contact Model. In 49th US Rock Mechanics/Geomechanics Symposium.
• Zhang, Q., Zhu, H. H., Zhang, L. Y., & others, . (2015). A new 3D Constitutive Model for Rock Mass Tunnel. In 49th US Rock Mechanics/Geomechanics Symposium.
• Chen, R., & Zhang, L. (2014). Mitigation of Mine Tailings Dust with Green Biopolymer. In Geo-Congress 2014 Technical Papers@ Geo-characterization and Modeling for Sustainability, 2198--2205.
• Ding, X., & Zhang, L. (2014). A New Contact Model for DEM Analysis of Rock. In 48th US Rock Mechanics/Geomechanics Symposium.
• Parameswaran, K., Ekholm, J., & Zhang, L. (2014). Evaluation of Mine Tailings Dust Control. In Geoenvironmental Engineering, GeoShanghai 2014, 80--89.
• Zhu, F., & Zhang, L. (2014). Experimental Study on Load-Unload Response Ratio (LURR) of Brittle Rocks. In Rock Mechanics and Its Applications in Civil, Mining, and Petroleum Engineering, GeoShanghai 2014, 5--12.
• Ahmari, S., Chen, R., & Zhang, L. (2012). Utilization of mine tailings as road base material. In GeoCongress 2012 State of the Art and Practice in Geotechnical Engineering, 3654--3661.
• Ding, X., & Zhang, L. (2012). Effect of model scale on mechanical properties of rocks based on PFC3D modeling. In 46th US Rock Mechanics/Geomechanics Symposium.
• Zhang, L., Ahmari, S., Sternberg, B., & Budhu, M. (2012). Feasibility Study of Compressed Air Energy Storage Using Steel Pipe Piles. In GeoCongress 2012, 4272--4279.
• Zhang, Q., Zhu, H., Zhang, L., & Ding, X. (2012). Effect of micro-parameters on the Hoek-Brown strength parameter mi for intact rock using particle flow modeling. In 46th US Rock Mechanics/Geomechanics Symposium.
• Ding, X., & Zhang, L. (2011, January). Simulation of rock fracturing using particle flow modeling: Phase I - Model development and calibration. In 45th US Rock Mechanics / Geomechanics Symposium.
  More info

  Abstract: This paper presents part of the results for the first phase of the research on simulating rock fracturing with particle flow modeling, using the three dimensional Particle Flow Code (PFC3D). The first phase work focuses on development and calibration of the numerical model based on the micro structure and laboratory mechanical test data (unconfined compressive strength, tensile strength and stress-strain curves) of real rocks. The results show that although the unconfined compressive strength can be well simulated using the standard PFC3D model, the tensile strength is over predicted and leads to unconfined compressive strength to tensile strength (UCS/T) ratios significantly lower than the laboratory test value. Two different methods have been used to improve the simulation results and increase the UCS/T ratio. The contact bond release model which simulates the pre-existent micro cracks in rock can double the UCS/T ratio from the standard PFC3D model but still under-predicts the UCS/T ratio. The near sphere clump particle model containing 50% clump particles only slightly improve the simulation results. Other methods and/or a combination of different methods need to be studied in order to develop a PFC3D model which can correctly simulate the mechanical behavior of real rocks. © 2011 ARMA, American Rock Mechanics Association.
• Zhang, L., & Radha, K. C. (2010, January). Stability analysis of vertical boreholes using a three-dimensional hoek-brown strength criterion. In Geotechnical Special Publication, GeoFlorida 2010 - Advances in Analysis, Modeling & Design, 283-292.
  More info

  Abstract: Borehole stability analysis plays an important role in the design of oil and gas well drilling. A main aspect of borehole stability analysis is the selection of an appropriate rock strength criterion. The two most commonly used rock strength criteria in borehole stability analysis are the Mohr-Coulomb criterion and the Drucker-Prager criterion. However, the Mohr-Coulomb criterion ignores the effect of the intermediate principal stress and is too conservative in estimating the critical overbalance pressure required to maintain borehole stability; while the Drucker-Prager criterion overestimate the effect of the intermediate principal stress and may result in non-sensible stability predictions. In this paper, a simple model based on a three-dimensional (3D) Hoek-Brown strength criterion is developed for stability analysis of vertical boreholes. Examples are presented to show the application of the 3D Hoek-Brown strength criterion for analyzing the stability of vertical boreholes and the results are compared with those using the Mohr-Coulomb and Drucker-Prager criteria. It shows that the 3D Hoek-Brown strength criterion predicts critical overbalance pressure values that are less conservative than those predicted by the Mohr-Coulomb criterion yet are not as unconservative as those predicted by the Drucker-Prager criterion. © 2010 ASCE.
• Zhang, L., Ralph, G., & Silva, F. (2010, January). Geotechnical safety program for underground storage caverns in salt. In 44th US Rock Mechanics Symposium - 5th US/Canada Rock Mechanics Symposium.
  More info

  Abstract: Considering the large volume and different types of material stored in salt caverns, it is important to ensure that the salt cavern be designed, constructed and operated safely. Since salt caverns are constructed in a geological formation, the structural safety problem of a salt cavern is essentially a geotechnical problem. In this paper, we describe the application of the Geotechnical Safety Program (GSP) to a gas storage cavern in salt, focusing on the first two components - performance criteria and design assessment. To develop the performance criteria, we considered performance aspects in different categories. For each performance aspect, we developed the performance criteria by determining the consequences of failure, selecting a tolerable level of risk, establishing criteria of performance, and ensuring that the criteria meet appropriate legal requirements and accepted standards of practice. The design assessment was conducted by checking the design conditions, identifying the critical mechanisms of performance, identifying typical and critical sections, reviewing the field and laboratory data, identifying major uncertainties and critical aspects of performance, and recommending actions to improve safety. Based on the design assessment, we identified several performance aspects which do not meet the performance criteria and recommended changes and/or measures so that the performance criteria can be met. Copyright 2010 ARMA, American Rock Mechanics Association.
• Zhang, L. (2009, March). Considering the effect of discontinuities in prediction of end bearing capacity of rock socketed shafts. In SinoRock2009 – ISRM International Symposium on Rock Mechanics: Rock Characterization, Modeling and Engineering Design Methods.
• Zhang, L., & Jinming, X. u. (2009, January). Axial load transfer behavior of rock-socketed shafts. In Geotechnical Special Publication, International Foundation Congress & Equipment Expo’09, 175-182.
  More info

  Abstract: In the design of rock-socketed shafts for supporting axial loading, the end bearing resistance is often ignored, resulting in excessive rock-socket lengths and increased cost. This paper investigates the axial load transfer behavior of rock-socketed shafts based on a database of 99 field test rock-socketed shafts. The shafts are 1.4 to 96.3 m long and have a diameter between 0.5 and 1.5 m. The rock-socket lengths are from 0 to 18.8 meters. The database is developed by collecting information on field test rocksocketed shafts from published papers and reports. The results show that it is important to account for the end bearing resistance in the design of rock-socketed shafts because (1) up to 25% of the shaft head load on average can be transmitted to and supported by the shaft base even at relatively small shaft head displacement in the working range of 5-15 mm, and (2) the portion of the shaft head load transmitted to and supported by the shaft base increases with time due to the effect of creep. © ASCE 2009.
• Zhang, L. (2008, January). Evaluation of three-dimensional Hoek-Brown strength criteria. In 42nd U.S. Rock Mechanics - 2nd U.S.-Canada Rock Mechanics Symposium.
  More info

  Abstract: In this paper, three three-dimensional (3D) versions of the Hoek-Brown strength criterion, respectively proposed by Pan and Hudson [1], Priest [2] and Zhang and Zhu [3], are briefly reviewed and evaluated. The evaluation shows that neither the Pan-Hudson criterion nor the Priest criterion will reduce to the form of the Hoek-Brown criterion at triaxial or biaxial stress state. Compared with the Hoek-Brown criterion, the Pan-Hudson criterion under-predicts the strength at triaxial stress state but overpredicts the strength at biaxial stress state. The Priest criterion predicts the same strength as the Hoek-Brown criterion at triaxial stress state but over-predicts the strength at biaxial stress state. The Zhang-Zhu criterion reduces to the form of the Hoek-Brown criterion at both triaxial and biaxial stress states and thus can be considered a true 3D version of the Hoek-Brown criterion. The three 3D strength criteria are also applied to analyze true triaxial compression test data of intact rocks collected from the published literature. Predictions of the Zhang-Zhu criterion are in good agreement with the test data for a range of different rock types, but the Pan-Hudson tends to under-predict and the Priest criterion tends to over-predict the strength of rocks. Copyright 2008, ARMA, American Rock Mechanics Association.
• Zhang, L. (2008, October). Predicting the end bearing capacity of rock socketed shafts. In 33rd Annual Conf. on Deep Foundations & 11th International Conference on Piling and Deep Foundations, 307-316.
• Zhang, L., Silva, F., & Grismala, R. (2003, October). Horizontal subgrade reaction coefficient of rock. In Soil and Rock America 2003, 2, 1931-1936.
• Silva, F., & Zhang, L. (2002, August). Geoenvironmental Engineering: Application of Geotechnical Fundamentals for Sustainable Development – State of the Practice. In Proc. of the VXII Venezuelan Geotechnical Seminar.
• Zhang, L., Silva-Tulla, F., & Grismala, R. (2002, January). Ultimate resistance of laterally loaded piles in cohesionless soils. In Geotechnical Special Publication, Deep Foundations 2002 – An International Perspective on Theory, Design, Construction, and Performance, 1364-1375.
  More info

  Abstract: A key element in the design of laterally loaded piles is the determination of the ultimate resistance that can be exerted by the soil against the pile. Several methods have been published for predicting the ultimate resistance of laterally loaded piles in cohesionless soils. However, these methods often produce significantly different ultimate resistance values. This makes it difficult for practical designers to effectively select the appropriate method when designing laterally loaded piles in cohesionless soils. By analyzing the lateral soil resistance distribution along the width of the pile and based on the test results of model rigid piles in cohesionless soils collected from the published literature, an expression is developed for the ultimate resistance (including frontal soil resistance and side shear resistance) of laterally loaded piles in cohesionless soils. Application of the developed expression to predict the lateral load capacity of laboratory and field rigid test piles in cohesionless soils gives satisfactory results.
• Zhang, L., & Einstein, H. H. (2000, June). Estimating the deformation modulus of rock masses. In 4th North American Rock Mechanics Symposium, Pacific Rocks 2000: Rock around the Rim, 703-708.