Experimental study on the characteristics of fault stick–slip behavior under different normal stresses

Abstract

Upon conducting simulated fault friction tests on granite specimens under various normal stresses utilizing CNL and CNS rock joint shear testers (RJST-616), we aimed to comparatively analyze the stick–slip behavior characteristics during fault sliding. Our results reveal that the sliding behavior of granite simulated faults under different normal stresses is primarily marked by stick–slip features. Both the static shear stress drop and the stick–slip time interval exhibit an exponential growth relationship with the normal stress, whereas the spatial frequency of stick–slip events demonstrates a negative correlation with the normal stress. Furthermore, we observed an exponential growth relationship between the critical slip weakening displacement and normal stress, with the growth rate showing a rapid and then slow trajectory. Additionally, we established an intrinsic connection between different seismic source parameters using normal stress as a bridge. Finally, we unveiled the occurrence and recovery mechanisms of fault stick–slip under varying normal stresses from the perspective of the friction cone. These findings not only enhance our understanding of the behavioral characteristics of fault stick–slip but also provide novel insights into the seismic evolution of natural fault systems.