Experiment and DEM simulation study on mechanical behaviors of shale under triaxial cyclic loading and unloading conditions

Abstract During shale gas exploration, natural fractures in reservoirs may be induced by cyclic loads frequently encountered different geological processes, including tectonic movements, seismic actions, and artificial construction interference (vertical horizontal wells drilling hydraulic fracturing). In this paper, experiments PFC 2D simulations are conducted to investigate the mechanical response mechanism of specimens under loading unloading. Using experimental simulation results, strength deformation characteristics strain energy damage evolutions during loading-unloading process quantified analyzed. The variable characterized plastic deformation, modulus, dissipated is thoroughly Based on simulation, micro-crack distribution evolution further studied, results can reflect well reveal loading. Furthermore, indicate that degree fatigue closely related number cycles undergo, a small not have distinct effect strength.