基于非饱和土强度理论的土质边坡浅层破坏稳定性分析  

Stability Analysis on Shallow Layer Failure of Soil Slope Based on Unsaturated Soil Strength Theory

作　　者：李修磊 陈洪凯[1] 李金凤 杨超 LI Xiulei;CHEN Hongkai;LI Jinfeng;YANG Chao(College of Traffic and Transportation,Chongqing Jiaotong Univ.,Chongqing 400074,China;Key Lab.of Geological Hazards Controlling on Three Gorges Reservoir Area of Ministry of Education,Three Gorges Univ.,Yichang 443002,China)

机构地区：[1]重庆交通大学交通运输学院,重庆400074 [2]三峡大学三峡库区地质灾害教育部重点实验室,湖北宜昌443002

出　　处：《工程科学与技术》2019年第2期61-70,共10页Advanced Engineering Sciences

基　　金：国家自然科学基金青年基金资助项目(41807276);中国博士后科学基金资助项目(2018M633627XB);2016年重庆高校创新团队建设计划资助项目(CXTDG201602012);重庆市首席专家工作室专项经费资助(201605)

摘　　要：基于非饱和土强度理论,建立边坡内单元土体达到临界破坏状态的判别方程,提出土质边坡浅层失稳由上缘张拉区、中间主滑动区和下缘挤压区组成的"上、下缘顺坡曲面"组合破坏模式;论证了采用对数螺旋线描述上、下缘滑动体破裂面形态的合理性,并采用极限平衡理论建立了适用于非饱和土质边坡浅层破坏的稳定性分析方法。结果表明:"上、下缘顺坡曲面"组合破坏稳定分析方法能够较好地反映滑坡深度zw与中间主滑动区范围L2之间的变化关系;对于饱和土质边坡,内摩擦角和边坡坡度对边坡稳定性的影响非常小,土体黏聚力的影响则要大得多;对于非饱和土质边坡,土体黏聚力和内摩擦角的减小及边坡坡度的增大均会显著减弱边坡浅层土体的稳定性;土质边坡处于临界状态(安全稳定系数FS=1.0)时,随着土体饱和度的增加潜在滑坡体的破裂面逐渐向浅层迁移,说明降雨入渗导致饱和度上升的土质边坡更容易发生浅层失稳破坏;对于有限长度的土质边坡,无限长斜坡稳定分析方法得到的稳定安全系数偏于保守,考虑了滑坡体上、下缘力学作用的组合破坏稳定分析方法更为合理准确。Based on unsaturated soil strength theory,a discriminant equation is established for the critical failure state of soil element in slope,and a combined failure mode of"upper and lower edge parallel slope curved surface"for soil slope is proposed,which includes three sliding regions composed of the tension zone at upper edge,the main slide zone in middle and the squeeze zone at lower edge.It is demonstrated that the failure surface morphology of the upper and lower edge sliding mass coincides with the logarithmic spiral.A new stability analysis method is established for unsaturated soil slope based on the limit equilibrium theory.The results shows that the relationships between landslide depth zw and main slide zone length L2 are better reflected using this combined failure mode of"upper and lower edge parallel slope curve".The stability of shallow soil slope decreases and tends gradually to the results of infinite slope stability with increase of the main slide zone length L2.For saturated soil slope,the effects of internal friction angle and slope angle on slope stability are very little,but the influence of cohesion is significant.For unsaturated soil slope,the slope stability is reduced apparently as cohesion and internal friction angle decreases and slope angle increases.As the soil slope is in critical state(i.e.safety factor FS=1.0),the sliding surface of potential landslide gradually migrates to the shallow layer with the increase of soil saturation.It indicates that the soil slope with rising saturation caused by rainfall is more prone to shallow failure.Compared with the traditional infinite length slope stability analysis method,for a finite length soil slope,this combined failure stability analysis method is more reasonability and accuracy because of the consideration of the mechanical effects of upper and lower edge zone.

关 键 词：非饱和土强度理论 土质边坡 浅层破坏模式 稳定分析 对数螺旋线 

分 类 号：TU441[建筑科学—岩土工程]