干湿循环对泥质砂岩力学特性及其微细观结构影响研究  

Influence of wetting-drying cycles on mechanical properties and microstructure of shaly sandstone

作　　者：刘新荣[1,2] 李栋梁[1,2] 张梁[1,2] 王震[1,2] 

机构地区：[1]重庆大学土木工程学院,重庆400045 [2]山地城镇建设与新技术教育部重点实验室(重庆大学),重庆400045

出　　处：《岩土工程学报》2016年第7期1291-1300,共10页Chinese Journal of Geotechnical Engineering

基　　金：2015重庆市研究生科研创新项目(CYB15038);国家自然科学基金项目(41372356)

摘　　要：以取自三峡库区某边坡的泥质砂岩为研究对象,通过单轴、三轴压缩试验,对不同干湿循环次数作用后泥质砂岩的物理力学特性进行了研究。借助SEM电镜扫描,对不同干湿循环次数作用后的泥质砂岩的微细观结构变化进行了探讨。研究发现:随干湿循环次数(1~20)的增加,泥质砂岩的峰值应力、弹性模量、黏聚力和内摩擦角都逐渐降低,峰值应变表现出下降、稳定两个阶段。其微细观结构变化总体上可归纳为整齐致密状、多孔团絮状和开裂紊流状3个阶段。基于离散元软件PFC^(2D),研究了干湿循环对泥质砂岩颗粒的接触网络,力链分布和裂纹分布的影响。基于试验数据拟合,对经历不同干湿循环次数作用的泥质砂岩的莫尔–库仑强度理论表达式进行了修正。The shaly sandstone which is taken from a slope of the Three Gorges Reservoir isstudied. Considering different wetting-drying cycles, the mechanical properties of shaly sandstone areinvestigated through uniaxial andtriaxial compression tests. The microstructural change law of shaly sandstone is alsostudied using thescanningelectronmicroscopy. The research reveals that with the increasing wetting-drying cycles （1-20）, the peak stress, elastic modulus, cohesion and internal friction angle of shaly sandstone decrease. But the peak strain showstwo stages offalling andstability. The microstructuralchange law of shaly sandstone can be summarized as three stages ofregular, porous and cracking properties. Byusingthe discrete element software PFC2D, the influences of wetting-drying cycles on contact network of shaly sandstone grains, distributionofchains and distribution ofcracks are studied. Based on the test results, the expression of Mohr-Coulomb strength theoryfor shaly sandstone is modified considering wetting-drying cycles.

关 键 词：干湿循环 泥质砂岩 力学特性 微细观 

分 类 号：TU411[建筑科学—岩土工程]