School of Civil and Environmental Engineering 

Ph.D. Thesis Defense Announcement 

Homogenization of Coupled Deformation, Damage and Diffusion Processes in Rocks and Finite Element Applications in Geomechanics and Geomorphology

By 

Tingting Xu

Advisor: 

Chloé Arson

Committee Members: 

Dr. Susan Burns (CEE); Dr. Sébastien Brisard (Laboratory Navier); Dr. Sheng Dai (CEE); Dr. Martial Taillefert (EAS); Dr. Yida Zhang (CU Boulder)
 

Date & Time: 

Tuesday, November 29, 2022; 10:00 AM EST

Location: 

Mason 2119; Zoom Meeting: 99394714810, Passcode: 000456

Eshelby’s solution will be extended to various degrees in this thesis. We developed computational frameworks that incorporate complex chemo-mechanical mechanisms across different scales. It is hoped that this work will contribute to a better understanding of mechanical and diffusion problems in composites that exhibit complex microscopic deformation and mass exchange processes. 

We begin by establishing a self-consistent approach for modeling coupled elastic and viscoplastic processes induced by dislocation and pressure solution in Chapter 2. Chapter 3 adds complexity to this mechanical problem by including imperfect interfaces between crystals. Building on the mechanical understanding of the effect of displacement jumps at the interface between inclusions and the HEM, we apply the concept of the imperfect interface to diffusion problems, considering flux discontinuities at the grain boundaries. In these two studies, the self-consistent scheme is used to capture the behavior of polycrystals.
 
In Chapter 4 and chapter 5, we study the effect of biotite weathering in granite. Granite properties are estimated with the Mori-Tanaka scheme, by considering biotite and microcrack inclusions. Chapter 4 presents a two-step Mori-Tanaka model that allows the prediction of anisotropic weathering-induced damage. The feedback effects between the propagation of discrete fractures, and the process of weathering (modeled by the extent of the weathering zone and the magnitude of the weathering rate) are investigated in Chapter 5. In these two chapters, the continuum model formulated at REV scale is implemented in the FEM software ABAQUS to simulate boundary value problems and test fundamental hypotheses that pertain to landscape evolution.