Numerical Simulation Investigation for Stress Deformation and Water Injection Seepage of Coal Microstructure under Uniaxial Compression

Abstract

Water transport in coal is a multiscale, multiphysical process that is affected by the coupling effect of multiple systems, such as pore and microfracture systems. In this study, numerical simulation of the microlevel of a coal matrix structure during simulated uniaxial compression mechanical experiments is performed. Based on the results, a realistic deformation pore structure model is developed to simulate coal seam water injection seepage. Under the effect of different loading directions, different results show that the distribution of pores and the loading direction of stress have a significant impact on the failure mode of coal matrix materials. As time proceeds, the porosity decreases from 64.2% to 61.7%. The porosity begins to increase again after 0.8 s. By setting the pressure gradient in the y-direction of the pore model to simulate seepage, the permeability of the coal matrix material is found to increase with the passage of time. A positive correlation exists between permeability and porosity. Avizo version 9.0, LS-DYNA version 14.0, and Fluent version 18.0 are used to study the mechanical characteristics of the pore structure of coal, as well as the seepage characteristics from the microperspective, which provides a new idea.