Abstract
Strong interactions between mechanical deformation and chemical reactions may play a critical role in the response of geomaterials or geological systems to evolving environmental circumstances that may occur in both natural and engineered processes. The present study focuses on mineral dissolution and precipitation at the intergranular contact whose consequences are often manifested at the macro-scale where the mechanical and transport properties of the geomaterial may be altered. Discrete element modeling is employed to explore two applications involving such mineral transformations. The first example is primarily focused on the chemo-mechanical coupling mechanisms of intergranular contact in the natural process of pressure solution and secondary compression. The effect of the mineral dissolution on the mechanical response at the grain contact is incorporated into the contact model. Discrete element simulations are performed to examine the overall mechanical response of particle assembles subject to mineral dissolution and the results demonstrate the important role of the kinetic rate characteristics of the dissolution process. The second part of the present study revolves around the effect of mineral precipitation in an engineered process known as microbially induced calcite precipitation for potential soil improvement. The kinetics of involved bio-chemical process is incorporated into on the contact model and the simulation results indicate considerable strengthening effect. Overall, the present study demonstrates the feasibility of discrete element approach as a numerical tool to model coupled chemo-mechanical phenomena across the scales.
Highlights
Micro-scale phenomena of mineral dissolution and precipitation in geomaterials may play a crucial role in the macroscopic processes of mechanical deformation and pore fluid transport
The presented coupled chemo-mechanical model is implemented in the discrete element analysis package PFC2D [35] using its programming language FISH to simulate the enhanced deformation affected by grain contact dissolution of two different sample minerals, mimicking “quartz” and “calcite”, the former characterized with a slow kinetic dissolution rate and the latter with a relatively faster dissolution rate
This present study explores a discrete element approach to modeling coupled phenomena of mechanical deformation and intrinsic chemical reaction processes
Summary
Micro-scale phenomena of mineral dissolution and precipitation in geomaterials may play a crucial role in the macroscopic processes of mechanical deformation and pore fluid transport. There have been growing interests in the behavior of geological materials or systems that are susceptible to the evolving environmental circumstances which often induce a strong interaction of chemical and mechanical processes. There is often a two-way coupling between chemically mediated deformation and mechanically enhanced reaction that may progress in a self-organized manner [2]. Such interactions often lead to the enhanced alteration of porosity, permeability, strength, stiffness, and other material properties. It is worth noting that such chemo-mechanical interactions are ubiquitous in natural processes, and may be considerably intensified or accelerated in anthropogenic processes enhanced by increased human activities, and in some cases even deliberately taken advantage of in engineering applications to accomplish certain desirable outcomes
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