Experimental investigation of fault slip modes and seismic characteristics in shale under typical stress paths

Abstract

Understanding fault slip behavior under different stress paths is essential for identifying the mechanical response of faults under varying loading conditions. This study examines five distinct stress paths to assess their impact on fault slip behavior and the associated acoustic emission (AE) characteristics. When the shear stress increases while the normal stress is maintained, the fracture exhibits creep behavior, characterized by gradual energy release and high b values. In contrast, when the normal stress decreases or when both shear and normal stresses increase, the fracture tends to exhibit stick–slip behavior, marked by abrupt energy release. A simultaneous decrease in shear and normal stresses leads to a gradual transition from creep-slip to stick–slip. Under conditions of increasing shear stress and decreasing normal stress, a mixed slip mode emerges. These results demonstrate that fault slip behavior is strongly dependent on the applied stress path, suggesting that stress paths should be carefully considered in engineering applications.