A rock bridge along the potential sliding surface of a rockslide has a relatively large bearing capacity and governs the stability of the rock slope. The physical and mechanical properties of specimens representing four rock bridge lengths were researched by direct shear experimentation. The micromechanism associated with the change in shear strength parameters was analyzed by PFC2D numerical simulations that corresponded to the experiments. The results revealed a rock bridge length effect, through which the peak shear strength increases with rock bridge shortening, accompanied by an increase in cohesion and a decrease in internal friction angle and main fracture surface roughness. Rock bridge shortening decreased the density of the microcracks at the shear stress peak point, changing the cohesive strength and frictional strength. The decrease in the internal friction angle could change the critical stress intensity factors to make shear cracks preferentially initiate over tensile cracks. Fracture roughness therefore decreased, inducing a lower residual shear strength. As a result, the difference in the peak and residual strengths increased with rock bridge shortening, which would promote brittle failure of the corresponding rock slope.

中文翻译：

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与岩桥长度效应相关的岩崩脆性破坏

沿着岩体滑坡潜在滑动面的岩桥具有较大的承载力，控制着岩体边坡的稳定性。通过直剪试验研究了代表四种岩桥长度的试件的物理力学性能。通过与实验相对应的 PFC2D 数值模拟分析与剪切强度参数变化相关的微观机制。结果揭示了一种岩桥长度效应，通过这种效应，峰值剪切强度随着岩桥的缩短而增加，伴随着内聚力的增加和内摩擦角和主断裂表面粗糙度的减小。岩桥缩短降低了剪切应力峰值点微裂纹的密度，改变了内聚强度和摩擦强度。内摩擦角的减小可以改变临界应力强度因子，使剪切裂纹优先于拉伸裂纹萌生。因此，裂缝粗糙度降低，导致残余剪切强度降低。结果，峰值强度和残余强度的差异随着岩桥缩短而增加，这将促进相应岩质边坡的脆性破坏。