School of Civil and Environmental Engineering
Ph.D. Thesis Defense Announcement
Numerical Modeling of Discontinuous Processes in Geomaterials and Geosystems
By Haozhou He
Advisor:
Chloé Arson (CEE)
Committee Members: Dr. Seth Busetti (ARAMCO), Dr. Sheng Dai (CEE), Dr. Daniel I. Goldman (PHYS) Dr. Lauren Stewart (CEE)
Date and Time: June 19th, 2023 at 1:00 PM
Location: (Hybrid) Mason 2119 and Zoom: https://zoom.us/j/95808728760?pwd=NzhmSVpiMk1ZOG1YRThlVTA4NFlJUT09
The complexity of geomaterials and the variation of their behavior under different conditions can significantly impact the success of geotechnical engineering projects. The development of new simulation techniques for geotechnical and geomechanical applications is of vital importance due to the increasing complexity of projects and inherent uncertainties in soil and rock behavior.
This doctoral research advances numerical methods for simulating discontinuous processes such as crack propagation, surface debonding and large deformation in geomechanics. Two novel approaches are presented to address the limitations of traditional Finite Element Methods (FEM) when dealing with discrete failure problems and soil-structure interactions. We first study multi-scale crack propagation in rocks. Most discrete fractures in rock propagate in combination with smaller defects (micro-cracks) that form a damaged zone around the discrete fracture surfaces. To account for the effects of micro-crack propagation, a new two dimensional 4-node cohesive element is defined to couple the Cohesive Zone Method (CZM) technique to a Continuum Damage Mechanics (CDM) model. The proposed CDM based CZ element is validated by single-element simulations, borehole breakout simulations, and biaxial compression simulations of textured materials. Next, we propose a novel approach to couple the Smooth Particle Hydrodynamics (SPH) method with the FEM to study large deformation processes in granular media that interact with solids. The SPH+FEM model is implemented in MATLAB to simulate the interaction between a solid (modeled with the FEM) and a host particulate medium (modeled with SPH). We use the proposed SPH+FEM to simulate various stress paths and boundary value problems of interest in geomechanics, e.g., problems of biaxial compression, sand column collapse, shallow foundation bearing capacity and wheeled locomotion. Lastly, we propose a comprehensive study of soil deformation mechanisms upon intrusion of compound anchors with a SPH+FEM model developed in LS-DYNA.