Report Topic: Computational Multiscale Modeling: A New Paradigm for Geotechnical Engineering
Reporter: Prof.Jidong Zhao, Hong Kong University of Science and Technology
Time: 10:00 am, Apr 10, 2015
Location: Academic hall of state key laboratory
Numerical simulations of geotechnical problems have long been based continuum models which are frequently phenomenological and lack adequate appreciation of the discrete nature of soils. Micromechanics-based methodologies, in particular those using Discrete Element Method, may offer rich microstructural information of soil response, but are largely limited to simulate “virtual” element tests only. We recently developed a hierarchical multi-scale framework to model geotechnical problems relevant to granular media wherein a rigorous hierarchical coupling between the finite element method (FEM) and the discrete element method (DEM) is employed. The FEM is used to discretize the macroscopic geometric domain of a boundary value problem into a FEM mesh. A DEM assembly with memory of its loading history is embedded at each Gauss integration point of the mesh to receive the global deformation from the FEM as input boundary conditions and is solved to provide the incremental stress-strain relation required at the specific material point to advance the FEM computation. The hierarchical framework helps to avoid the phenomenological nature of conventional continuum approaches of constitutive modeling, while retaining the computational efficiency of the FEM in solving large-scale boundary value problems (BVPs). It meanwhile facilitates a thorough cross-scale understanding on the behavior of granular media. The hierarchical structure also offers great convenience for its implementation of parallel computing which greatly enhances its computational efficiency. The predictive capability of the proposed framework is demonstrated by its application to resolving fundamental soil mechanics puzzles such as strain localization, liquefaction, anisotropy, non-coaxiality, fabric evolution as well as simulation of more practical problems in geotechnical engineering including footing, retaining wall and cavity expansion. We further discuss the potential barriers that obstruct the proposed framework to become a paradigm shift for next generation geotechnical analysis and design.
Dr. Jidong Zhao is Associate Professor in Geomechanics at Hong Kong University of Science and Technology. He received both his Bachelor Degree and Ph.D. from Tsinghua University. Prior to his current post, he has worked as a postdoc fellow and later as a University Lecturer at the University of Newcastle, Australia. He serves on the editorial board for Computers and Geotechnics (Elsevier) and received the “Outstanding Reviewer Award” of the journal in 2014. He is a Guest Editor for Granular Matter (Springer), and is also regularly invited to review papers by over 20 leading journals in geotechnics, applied mechanics and numerical methods. Dr. Zhao is also an invited proposal assessor for funding agencies including Australian Research Council (ARC), Natural Sciences and Engineering Research Council of Canada (NSERC), Chilean National Science and Technology Commission (CONICYT) and Research Grants Council of Hong Kong (RGC/HK). His major research interests include constitutive modeling of soils, computational geomechanics, multiscale/multiphysics modeling of granular media. More information on Dr. Zhao and his research can be found via his homepage: http://ihome.ust.hk/~jzhao/.
