干湿循环作用下片岩片理面抗剪性能劣化实验设计  

Experimental design on shear degradation of schistosity plane under dry-wet cycles

作　　者：李志刚 李洋 代云云 朱德胜 李春红 徐光黎[2] LI Zhigang;LI Yang;DAI Yunyun;ZHU Desheng;LI Chunhong;XU Guangli(College of Architectural Science and Engineering,Yangzhou University,Yangzhou 225127,China;Faculty of Engineering,China University of Geosciences(Wuhan),Wuhan 430074,China)

机构地区：[1]扬州大学建筑科学与工程学院,江苏扬州225127 [2]中国地质大学(武汉)工程学院,湖北武汉430074

出　　处：《实验技术与管理》2024年第6期41-46,共6页Experimental Technology and Management

基　　金：国家自然科学基金项目(41772314);教育部产学合作协同育人项目(202102542005);扬州大学教学改革研究课题(YZUJX2022—D13);扬州大学教学改革研究课题(本科生学科竞赛专项)(xkjs2021030)。

摘　　要：为揭示片岩片理面在干湿循环作用下抗剪性能劣化规律,选取云母石英片岩设计相应的直剪实验方案进行研究,并将该方案应用于实验教学。实验结果表明:干湿循环作用下,片理面抗剪性能劣化明显,干湿循环20次后,粘聚力和内摩擦角分别下降49.05%、15.34%,粘聚力下降幅度约为内摩擦角的3.2倍;片理面不断渗出黄褐色物质浸染岩样,使片理面逐渐显化,且逐渐沿片理面产生裂隙并不断向岩石内部扩展发育;片理面是水进出片岩内部的良好通道,水可将片理面间的泥质胶结物和可溶性矿物溶解并带出,使得片理面间胶结物及胶结面积逐渐减少,抗剪性能逐渐劣化。该实验教学对培养学生科研创新思维及理论联系实际能力具有重要意义。[Objective]The schistosity plane,a common weak structural feature in schist formations,serves as a conduit for water transfer and storage and is an active zone for water-rock interaction within schist.However,under the cyclical conditions of rainfall and evaporation,the mechanical properties of the schistosity plane tend to deteriorate.This degradation reduces the stability of schist slopes and contributes to frequent geological hazards such as landslides and collapses.Hence,conducting experimental research on the degradation of schistosity planes under dry-wet cycles is essential.Such research aims to uncover the patterns of degradation,vital for long-term stability assessments of schist slopes,and to nurture students’ability to integrate theory with practical application.[Methods]In this study, cylindrical samples with an aspect ratio of 1∶1 were prepared and subjected to dry-wet cycle treatments. During the drying phase, the samples were exposed to a temperature of 105 ℃ for 24 hours, while for wetting, the free water absorption method was employed, during which the samples were soaked for 24 hours. Subsequently, direct shear tests were conducted on the samples after 0, 1, 3, 5, 10, 15, and 20 cycles of dry-wet treatment, with normal stress levels set at 3, 6, 9, 12, and 15 MPa, respectively, to determine the corresponding peak shear stress. Following the Mohr-Coulomb failure criterion, cohesive force and internal friction angle of the schistosity plane were fitted. Additionally, the total deterioration degree and stage deterioration degree were calculated using respective deterioration degree formulas. Finally, the apparent changes in the schist samples were observed, and the deterioration mechanism was elucidated by correlating it with the law of shear strength. [Results] The experimental findings revealed the following: 1) The degradation rate of peak shear stress, cohesion force, and internal friction angle was more rapid and pronounced in the initial stages but slowed down and became smaller in the

关 键 词：云母石英片岩 片理面 干湿循环 抗剪性能 劣化实验 

分 类 号：TU458.3[建筑科学—岩土工程]