Study on Rock Type Effect of Fault Sliding Stability

The protolith of the hanging wall and footwall of a fault plays a crucial role in influencing the sliding stability of the fault, and different protoliths have different tendencies toward sliding instability. To investigate the influence of protoliths on fault sliding stability, simulated fault friction sliding tests were conducted on five types of rocks: fine sandstone, limestone, marble, basalt, and granite, under various loading conditions. The test results demonstrate that, under the same loading conditions, basalt and granite exhibit a greater inclination toward unstable sliding during fault simulation, primarily displaying regular stick–slip and regular inclusion chaotic stick–slip behaviors. On the other hand, fine sandstone, limestone, and marble are predominantly characterized by stable sliding behaviors. The order of sensitivity for the influencing factors on sliding mode is the type of protolith, followed by initial normal stress, and then displacement loading rate. Based on the type of protolith and loading conditions (initial normal stress and displacement loading rate), the sliding mode can change during the sliding process of the simulated rock faults, transitioning from stable sliding to chaotic stick–slip, and then to regular stick–slip. Alternatively, the sliding mode can shift from regular inclusion chaotic stick–slip to regular stick–slip, or from regular stick–slip to stable sliding. Finally, the complexity of sliding patterns in different types of protoliths is analyzed from the perspectives of mineral composition and microstructure, elucidating the underlying mechanisms behind three sliding patterns: stable sliding, chaotic stick–slip, and regular stick–slip. Furthermore, the degree to which different types of rocks tend toward stick–slip behavior can be ranked as follows: rock mineral composition, mineral particle size, and structure among rock minerals. These research findings contribute to a deeper understanding of fault sliding behavior.