Cyclic shear behavior of en-echelon joints under constant normal stiffness conditions  

作　　者：Bin Wang Yujing Jiang Qiangyong Zhang Hongbin Chen Richeng Liu Yuanchao Zhang 

机构地区：[1]Graduate School of Engineering,Nagasaki University,Nagasaki,852-8521,Japan [2]Research Center of Geotechnical and Structural Engineering,Shandong University,Ji’nan,250061,China [3]State Key Laboratory for Geomechanics and Deep Underground Engineering,China University of Mining and Technology,Xuzhou,221116,China [4]College of Civil Engineering,Fuzhou University,Fuzhou,350108,China

出　　处：《Journal of Rock Mechanics and Geotechnical Engineering》2024年第9期3419-3436,共18页岩石力学与岩土工程学报（英文版）

基　　金：financially supported by the National Natural Science Foundation of China(Grant No.42172292);Taishan Scholars Project Special Funding,and Shandong Energy Group(Grant No.SNKJ 2022A01-R26).

摘　　要：To reveal the mechanism of shear failure of en-echelon joints under cyclic loading,such as during earthquakes,we conducted a series of cyclic shear tests of en-echelon joints under constant normal stiffness(CNS)conditions.We analyzed the evolution of shear stress,normal stress,stress path,dilatancy characteristics,and friction coefficient and revealed the failure mechanisms of en-echelon joints at different angles.The results show that the cyclic shear behavior of the en-echelon joints is closely related to the joint angle,with the shear strength at a positive angle exceeding that at a negative angle during shear cycles.As the number of cycles increases,the shear strength decreases rapidly,and the difference between the varying angles gradually decreases.Dilation occurs in the early shear cycles(1 and 2),while contraction is the main feature in later cycles(310).The friction coefficient decreases with the number of cycles and exhibits a more significant sensitivity to joint angles than shear cycles.The joint angle determines the asperities on the rupture surfaces and the block size,and thus determines the subsequent shear failure mode(block crushing and asperity degradation).At positive angles,block size is more greater and asperities on the rupture surface are smaller than at nonpositive angles.Therefore,the cyclic shear behavior is controlled by block crushing at positive angles and asperity degradation at negative angles.

关 键 词：En-echelon joint Cyclic shear tests Shear stress Normal displacement Constant normal stiffness(CNS) 

分 类 号：TU4[建筑科学—土工工程]