粗糙节理的峰值抗剪强度准则

采用3组具有不同表面形貌的节理试件分别在0.5，1.0，1.5，2.0，3.0 MPa的法向应力下进行直剪试验，研究常法向应力条件下峰值抗剪强度与节理表面三维形貌特征参数之间的定量关系。选用有效三维平均倾角、最大可能接触面积比作为表征节理三维形貌特征的参数；在分析剪胀角与法向应力关系的基础上基于试验结果提出双曲线形式的经验剪胀角模型，进而建立新的节理峰值抗剪强度公式。与Barton公式、Son公式进行了对比，在分析计算偏差的基础上对新公式做出简要评价。

New peak shear strength criteria for roughness joints

Simulated rock joint samples with different surface topographies are casted by cement paste. A series of direct shear tests under 5 levels of normal stresses, 0.5, 1.0, 1.5, 2.0 and 3.0 MPa, respectively, are performed in order to study the relationship between joint peak shear strength and its three-dimensional surface topography. Effective joint three-dimensional surface mean dip angle and the maximum possible contact area ratio are selected to describe the joint roughness character. Based on the experimental results, a new empirical equation is proposed for these joints by satisfying the peak dilation angle boundary conditions under zero and very high normal stress. Then, new joint peak shear strength criterion is presented. The calculated results by means of the new criterion are compared with the well-known shear strength criteria, such as the Barton?s criteria and Son criteria, and the results show that the Barton?s criteria underestimate the observed peak strength. At last, on the basis of analysis of deviation, the new criterion is also evaluated.