认知循环剪切荷载作用下节理剪切强度的劣化机制并提出相应的分析模型，是准确评价地震荷载作用下岩体工程安全的重要基础之一。基于不同起伏角度、强度等级的人工节理试样在多种法向应力下的循环剪切试验结果，分析循环剪切的试验曲线特点及表面凸起体的破坏过程和残余凸起体的形态特征，提出表征节理表面凸起体形态变化过程的概化破坏模型。利用提出的破坏模型，分别确定剪胀角与剪胀率、凸起体剪断率以及表面基本摩擦角之间的表达关系；并引入到 Ladanyi-Archambault 剪切强度公式中，建立以剪胀角经验公式和 Ladanyi-Archambault剪切强度公式为基础的节理循环剪切强度公式。最后将部分试样的剪切强度计算值与试验值进行对比，结果表明计算值与试验值总体上吻合较好，高起伏角度节理试样存在一定偏差。%Degradation mechanism of the shear strength of rock joints under cyclic shear loading and corresponding analysis model are bases for accurate assessment of rock engineering safety under seismic load. Joint specimens with three kinds of joint wall strengths and five kinds of asperity angles were prepared,then a series of cyclic shear tests were performed under four normal stress levels. Test curves,destruction process of tooth-asperity and the residual form of tooth-asperity were discussed according to test results. And further,a generalized damage model for residual form of tooth-asperity is proposed. Using the proposed model,the mathematical relationships between snipped rate of tooth-asperity,dilation rate,angle of base friction and average dilation angle were established separately. In addition,an empirical formula of the average dilation angle was given according to the cyclic shear experimental results. Thus,the cyclic shear strength calculation formula was established based on the average dilation angle formula and Ladanyi-Archambault shear strength formula. Finally,calculation results of cyclic shear strength were compared with test results. It is indicated that,the calculation results have good agreement with the test results,but there exists certain deviation for the high angle joints specimens.
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