节理的剪切力学性质与含三维形貌参数的剪切强度准则比较研究

利用水泥砂浆材料浇注3组不同表面形貌的节理试件,由常法向应力下的直剪试验研究节理的剪切力学性质,并分析法向应力、三维形貌特征对抗剪强度的影响。直剪试验结果表明：峰值剪胀角与法向应力成反变化关系,与粗糙程度呈正变化关系；峰值抗剪强度与法向应力、粗糙程度均呈正变化关系。分析了JRC-JCS准则计算值偏低于试验值的原因,根据试验现象建议采用三维形貌参数、抗拉强度描述节理的剪切强度。对比分析了含三维形貌参数的峰值抗剪强度准则,建议低法向应力水平下采用双曲线形式的峰值剪切强度准则估算岩石节理的峰值抗剪强度。

Shear behavior of rock joints and comparative study on shear strength criteria with three-dimensional morphology parameters

Three groups of rock joints with different morphologies are made from cement mortar materials. The shear behavior is investigated by means of the direct shear tests under constant normal stress condition. The effects of the applied normal stress and morphology on the shear strength are analyzed. According to the experimental results, it can be found that the peak dilatancy angle decreases with the increasing normal stress and increases with the increasing roughness. The shear strength increases with the increasing normal stress and also the roughness of rock joints. The reason of underestimation by JRC-JCS criterion is analyzed, and it is suggested to adopt the three-dimensional morphology parameters and tensile strength to capture the characteristics of the peak shear strength. The hyperbolic criterion is suggested to use as a predictive tool to assess the peak shear strength of rock joints under low normal stress level based on the comparisons among several criteria with three-dimensional morphology parameters.