This paper aims to identify and quantitatively evaluate various critical mechanisms associated with the processes of desiccation shrinkage and cracking in drying silty soils. A previously developed 1D bundle-of-tubes model is refined to simulate the various stages of drying shrinkage in 2D, using the actual pore size distribution based on Mercury Intrusion Porosimetry (MIP) data. Experimental evidence at a meso-scale has shown that the air entry phenomenon may occur in two possible scenarios: air incursion at the external surface and formation of vapor nucleus in the interior. Further transition of solid-water structural configuration into funicular and pendular states from initially capillary state is simulated.

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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.