砒砂岩抗剪强度与其结构特征关系  

Relationship between shear strength and structural characteristics of Pisha sandstone

作　　者：伍艳[1,2] 蔡怀森[2] 刘慧[2] 杨忠芳[1] WU Yan;CAI Huaisen;LIU Hui;YANG Zhongfang(School of Earth Sciences and Resources,China University of Geosciences (Beijing),Beijing 100083,China;Yellow River Institute of Hydraulic Research,Zhengzhou 450003,China)

机构地区：[1]中国地质大学(北京)地球科学与资源学院,北京100083 [2]黄河水利科学研究院,河南郑州450003

出　　处：《水利水电科技进展》2019年第5期21-26,共6页Advances in Science and Technology of Water Resources

基　　金：国家重点研发计划(2017YFC0504503);“十二五”国家科技支撑计划(2013BAC05B01);中央级公益性科研院所基本科研业务费专项(HKY-JBYW-2016-23)

摘　　要：通过直剪试验、X射线衍射、电镜分析的方法,分析了红色砒砂岩和白色砒砂岩力学性能随含水率的变化规律,观测了砒砂岩的颗粒粒径分布、矿物组成及微观形貌,探讨了砒砂岩结构特征对抗剪强度的影响。结果表明,含水率对红色和白色砒砂岩抗剪强度的影响不同,红色砒砂岩抗剪强度随含水率增大先增大后减小,黏聚力起主导主用,白色砒砂岩抗剪强度随含水率增大而减小,摩擦力和咬合力起主导作用;红色和白色砒砂岩的主要矿物是石英、长石、蒙脱石和方解石,长石的易于风化,蒙脱石的遇水膨胀及方解石的易分解,导致砒砂岩力学性能较差;白色砒砂岩以粗砂为主,含少量细砂,颗粒有明显棱角,孔隙较大,导致颗粒间具有较强的摩擦力和咬合力,而红色砒砂岩细砂含量较多,结构连接较致密,导致滑动过程中以黏聚力为主导,咬合摩擦作用较弱。The mechanical properties of red and white Pisha sandstone with moisture content were investigated by direct shear test, X-ray diffraction and electron microscope analysis. The particle size distribution, mineral composition and micromorphology of Pisha sandstone were observed, and the influence of structural characteristics of Pisha sandstone on shear strength was also discussed. The results show that moisture content has different effects on the shear strength of red and white Pisha sandstone. The shear strength of red Pisha sandstone increases first and then decreases with the increase of moisture content dominated by the cohesive force, and the shear strength of white Pisha sandstone decreases with the increase of moisture content dominated by the friction and bite force. The main minerals of red and white Pisha sandstone are quartz, feldspar, montmorillonite and calcite. The easy weathering of feldspar, easy water expansion of montmorillonite, and the easy decomposition of calcite lead to the poor mechanical properties of Pisha sandstone. The white Pisha sandstone is composed of coarse sand and a small amount of fine sands. The particles have obvious edges and large pores, which lead to strong friction and bite force among the particles. The red Pisha sandstone is mainly composed of fine sand, and the structure is more compact, so in the sliding process, cohesion is the dominant factor, and the frictional action is less important.

关 键 词：抗剪强度 微观形貌 结构特征 砒砂岩 含水率 

分 类 号：TV882.1[水利工程—水利水电工程] TU457[建筑科学—岩土工程]