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节理的三维形貌特征是影响节理剪切力学行为的重要因素。为了深入研究三维形貌特征对岩石节理峰值抗剪强度的影响,制备花岗岩和红砂岩人工劈裂岩石节理试样,并在常法向应力条件下进行了2种岩样节理的直剪试验,法向应力变化范围为0.325~8.000 MPa。在直剪试验前对节理表面形貌进行测量,并计算其三维形貌参数最大接触面积比A0、最大有效剪切倾角θ*max和粗糙度参数C。通过对三维形貌参数和直剪试验结果的分析,基于三维形貌参数最大有效剪切倾角θ*max和粗糙度参数C,建立节理峰值抗剪强度模型。最后,引用Grasselli的30组直剪试验数据对模型进行验证计算,并结合本文的20组试验数据,与Grasselli和夏才初的节理强度模型进行对比分析,结果表明新模型有合理的改进,而且能够很好地预测节理的峰值抗剪强度。
The three-dimensional topography of joints is an important factor that influences the shear behavior of joints. In order to further study the effect of three-dimensional topography on the peak shear strength of rock joints, artificial joint specimens of granite and red sandstone were prepared, and the direct shear tests of two kinds of rock specimen joints under normal normal stress were carried out. The normal stress range of 0.325 ~ 8.000 MPa. The joint surface topography was measured before the direct shear test, and the maximum contact area ratio A0, the maximum effective shear angle θ * max and the roughness parameter C of the three-dimensional topography parameters were calculated. Based on the analysis of the three-dimensional topography parameters and the direct shear test results, the joint peak shear strength model was established based on the maximum effective shear inclination θ * max and the roughness parameter C of the three-dimensional topography parameters. In the end, Grasselli’s 30 sets of direct shear test data are used to verify and calculate the model. Comparing with the 20 sets of experimental data in this paper, the results are compared with the joint strength models of Grasselli and Xia Caichu. The results show that the new model has a reasonable improvement, Good prediction of the joint peak shear strength.