土石混合料-基岩接触面剪切力学特性及剪切带变形特征研究  

Study on shear mechanical properties and deformation characteristics of shear zone of soil-rock mixture-bedrock interface

作　　者：杨忠平[1,2,3] 刘浩宇 李进 李绪勇[1,2,3] 刘新荣 YANG Zhongping;LIU Haoyu;LI Jin;LI Xuyong;LIU Xinrong(School of Civil Engineering,Chongqing University,Chongqing 400045,China;State Key Laboratory of Coal Mine Disaster Dynamics and Control,Chongqing University,Chongqing 400044,China;National Joint Engineering Research Center of Geohazards Prevention in the Reservoir Areas(Chongqing),Chongqing 400045,China)

机构地区：[1]重庆大学土木工程学院,重庆400045 [2]重庆大学、煤矿灾害动力学与控制国家重点实验室,重庆400044 [3]库区环境地质灾害防治国家地方联合工程研究中心(重庆),重庆400045

出　　处：《岩石力学与工程学报》2023年第2期292-306,共15页Chinese Journal of Rock Mechanics and Engineering

基　　金：重庆市自然科学基金面上项目(cstc2021jcyj-msxmX0558);国家自然科学基金资助项目(42177125,41972266)。

摘　　要：土石混合料-基岩接触面剪切力学特性因受多种因素影响而极其复杂,其中,界面细观形态是影响剪切力学特性及剪切带变形特征的重要因素之一。基于大型叠环单剪试验以及PFC2D数值模拟,揭示基岩界面细观形态对土石混合料-基岩界面剪切力学特性和剪切带特征以及演化规律的影响。结果表明:接触面抗剪强度随粗糙度增大而增大;粗糙度为表观黏聚力主要控制因素,当粗糙度由8.9增至11.5时,表观黏聚力提高95.3%;粗糙度对界面摩擦角的影响作用较小,界面摩擦角在27°上下波动。界面细观形态凹槽结构在一定倾斜角度内可发生“自锁”效应,凹槽内土石形成锁固体,锁固体可增大接触面抗剪强度,控制剪切带沿其外轮廓发展,出现“绕石”现象。平缓界面处块石具有“滞后效应”,易与周边土石形成强度远小于锁固体的“类锁固体”,控制剪切带绕其外轮廓与基岩界面分岔发展,使剪切带出现“包石”现象。基于能量变化,将剪切过程分为3个阶段:剪密阶段:应变能与摩擦能快速增长;线性增加阶段:应变能与摩擦能增长速率比例近似保持9∶1;应变硬化阶段:应变能占比持续下降,但仍占据主导地位。The interface shear mechanical properties of soil-rock mixture and bedrock are complex,and the mesomorphology of the interface has an important influence on the shear mechanical properties and the deformation characteristics of the shear zone.Based on simple shear test and numerical simulation,the shear mechanical properties,shear zone characteristics and evolution law of the interface between soil-rock mixture and bedrock with different mesoscopic morphology were researched.The results show that the Roughness is the main controlling factor of cohesion.When roughness increases from 8.9 to 11.5,cohesion increases by 95.3%.Roughness has little effect on the interface friction angle,which fluctuates at 27°.The anchor effect can occur in the micro-groove structure at a certain inclination angle,and the soil and stone in the groove form anchor solid,which can increase the shear strength of the interface and control the development of shear band along its outer contour,namely socalled surrounding stone phenomenon.The block rock at the gentle interface has hysteresis effect,and is easy to form false anchor solid with the surrounding soil and stone,which is much less strong than the anchor solid,and controls the bifurcation development of the shear zone around its outer contour and the bedrock interface,resulting in the phenomenon that shear encloses the stone in the shear zone.Based on energy changes,the shear process can be divided into three stages:at the beginning of shear,the strain energy and friction energy increase rapidly,which is the shear densification stage.The proportion of strain energy and friction energy growth rate is approximately 9:1,which is a linear increase stage.At the end of shearing,the strain energy ratio continues to decrease,but still occupies a dominant position,which is the strain hardening stage.

关 键 词：土力学 土石混合体 粗糙度 界面形态 剪切带 数值模拟 

分 类 号：TU43[建筑科学—岩土工程]