The influence of faults on adjacent rock mechanical behavior and acoustic emission characteristics: A case study of the xianshuihe fault zone

Abstract

Tensile strength is a crucial parameter for assessing rock stability and fracture characteristics, which play a significant role in the prediction and engineering design of geohazards. However, fault slip activity can weaken the strength of the surrounding rock mass, thereby influencing its mechanical behavior and failure mode. This study investigates the spatial variation of the tensile strength (σ_t), compressive strength (σ_c), P-wave velocity (V_p), and acoustic emission (AE) characteristics at varying distances from the Xianshuihe Fault zone (XSHF), focusing on three representative profiles. The results show that the σ_t, σ_c, and V_p significantly decrease near the fault (0–5 ​km). Specifically, the relative change rates of σ_t, σ_c, and V_p at approximately 5 ​km from the fault are 1.55–1.8 times, 1.22–1.86 times, and 1.02–1.25 times greater, respectively, compared to the near-fault zone. As the distance from the fault increases (10–20 ​km), the rock integrity improves, and the mechanical properties recover. AE monitoring reveals increased microcracks near the fault, with higher b-value and dominant tensile failure modes. Further from the fault, the rock exhibits increased brittleness, and tensile cracking becomes more prevalent. Overall, the mechanical parameters and AE characteristics demonstrate predictable spatial variation with distance, providing valuable insights for identifying stress concentration zones and potential geohazards.