Abstract The Mohr-Coulomb (MC) shear strength parameters, cohesion c and angle of friction φ, are required in numerical models. Currently, the geological strength index (GSI) system has been widely used for estimating shear strength of blocky rock masses in rock engineering. However, the GSI system does not include the effect of joint orientation β on the mechanical properties of a rock mass, which means that the shear strength model cannot reflect anisotropic rock mass strength behavior caused by joint orientation. In this research, UDEC-based synthetic rock mass models, which are calibrated by experimental data, are adopted to study the effect of joint orientation on the shear strength of blocky rock masses with two perpendicular joint sets. The values of cohesion c and angle of friction φ estimated from the numerical simulation are compared with those calculated from the empirical shear strength models based on the GSI system. Comparison of the results shows that the existing empirical model overestimates the shear strength of rock mass when 10°

中文翻译：

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具有持续节理的各向异性块状岩体的抗剪强度模型

摘要 数值模型需要摩尔-库仑 (MC) 剪切强度参数、内聚力 c 和摩擦角 φ。目前，地质强度指数（GSI）系统已广泛用于岩石工程中块状岩体抗剪强度的估算。然而，GSI 系统不包括节理取向β 对岩体力学特性的影响，这意味着抗剪强度模型不能反映节理取向引起的各向异性岩体强度行为。本研究采用基于UDEC的合成岩体模型，通过实验数据标定，研究节理方向对具有两个垂直节理组块状岩体抗剪强度的影响。将数值模拟估计的内聚力 c 和摩擦角 φ 的值与基于 GSI 系统的经验剪切强度模型计算的值进行比较。结果对比表明，现有经验模型高估了10°时岩体的抗剪强度