Experimental and numerical investigation of microstructure effect on the mechanical behavior and failure process of brittle rocks

The microscopic characteristics greatly influence the nonlinear mechanical behavior and failure process of rock materials. In the present work, the experimental investigations are firstly performed including microstructural observations and macroscopic laboratory tests. Based on various experimental evidences, a micromechanical damage model is proposed according to the microscopic characteristics for the description of the local mechanical features such as mineralogical composition, plastic deformation and failure process caused by induced damage. The microstructure of the studied rocks is artificially reconstructed using Fast Fourier Transforms (FFT) based technique without meshing the complex geometry composed of clay matrix and two randomly distributed mineral inclusions. Comparisons between experimental data and numerical predictions are presented for uniaxial and triaxial compression tests. The characterization of damage evolution is visualized by the direct full field numerical simulations corresponding the macroscopic mechanical response. The effects of induced damage, the confining pressure and the overburden depth on the nonlinear mechanical behavior and failure process are schematically studied.