Shear weakening behavior at the surface of structural plane of rock

作     者：He, Liu Zhao, Zhi-Ming Wu, Guang Liu, Di-Yi 

作者机构：Faculty of Geosciences and Environmental Engineering Southwest Jiaotong University Chengdu 611756 China 

出 版 物：《Yantu Lixue/Rock and Soil Mechanics》 (Rock Soil Mech)

年 卷 期：2020年第41卷

页      面：19-29页

核心收录：

基　　金：This work was supported by the National Natural Science Foundation of China(41602293) 

主　　题：Surface morphology 

摘      要：Based on a series of direct shear test results of structural planes of similar materials of rock mass, the initial morphology of different structural planes Z2, structural surface wall strength JCS and normal stress σn on the shear weakening and failure of structural surfaces are studied under different shear displacement conditions by applying the three-dimensional scanning identification technique. The results show that the surface damage coefficient (N) of the joint surfaces with higher Z2(initial), JCS and σn increases significantly at different shear displacements with the continuous increase of shear displacement. Structural surfaces with a much higher JCS value are dominated by brittle failure, while structural surfaces with a smaller JCS value are dominated by wear-out failure. During the shear process, the weakening of the structural surface morphology is caused by the shear effect of the surface protrusion, and also the filling effect of the depressed area of the structural plane. Based on the degradation rate of the morphology factor of structural plane Z2(δ) at different shear displacement, the degradation process of joint surface was classified into three stages with the shear displacement: the initial degradation stage, rapid degradation stage, and constant degradation stage. With the increase of Z2(initial), JCS and σn, the segmentation characteristics of degradation of structural planes become much more obvious, and the transformation process of three stages has an accelerating trend. An empirical model of joint surface morphology degradation under the influence of different factors is proposed through the regression analysis. The results indicate that the accurate tracking on the weakening characteristics of the structural surface morphology during the shearing process is beneficial to study the evolution of mechanical properties of the structural surfaces during the shearing process. © 2020, Science Press. All right reserved.