滑带土环剪试验及其对水库滑坡临滑强度的启示  

Ring shear tests on slip soils and their enlightenment to critical strength of reservoir landslides

作　　者：范志强 唐辉明[1,2] 谭钦文[1] 杨迎铭 温韬[1] FAN Zhi-qiang;TANG Hui-ming;TAN Qin-wen;YANG Ying-ming;WEN Tao(Faculty of Engineering,China University of Geosciences,Wuhan 430074,China;Three Gorges Research Center for Geo-hazard,Ministry of Education,Wuhan 430074,China;University College London,London WC1E 6BT,England)

机构地区：[1]中国地质大学(武汉)工程学院,湖北武汉430074 [2]中国地质大学(武汉)教育部三峡地质灾害研究中心,湖北武汉430074 [3]伦敦大学学院,英国伦敦WC1E6BT

出　　处：《岩土工程学报》2019年第9期1698-1706,共9页Chinese Journal of Geotechnical Engineering

基　　金：国家重点研发计划项目（2017YFC1501300）

摘　　要：滑坡临滑强度在滑坡研究中是一项重要内容,如何准确地确定其值是长期以来的重点和难点。开展滑带土环剪试验,不仅可以获取土体峰残强度参数,且能揭示土体剪切力学特性。通过黄土坡滑坡滑带土的环剪试验,确定出以180 kPa为界的高、低法向压应力区间,并分区间进行了土体剪切强度研究,分析了滑带土的剪切力学分区特性。揭示出本次滑带土以黏聚力下降为主(高压应力区下降44.8%,低压应力区下降93.8%),而摩擦角几乎不变(高、低压应力区峰残摩擦角之差分别为0.136°,0.468°)的峰后强度弱化机制。结合试验,通过引入黏聚力弱化系数,采用一种能反映滑坡演化过程的临滑强度反演方法,研究了不同工况下水库滑坡的临滑强度。并且从坡体受力状态和强度参数弱化的层面探讨了临滑强度因工况而异的原因,阐明其启示意义和工程意义。The critical strength of landslides is important for their researches, and how to evaluate it accurately has been the focus and nodus. Conducting ring shear tests on slip soils can obtain the peak and residual strength parameters, and it is helpful to reveal the shearing properties of the soils. Thus, the ring shear tests on the slip soils sampled from Huangtupo landslide are carried out, and two normal stress partitions(namely high-and low-stress subareas) are determined with the boundary stress value of 180 kPa. Then, the soil strengths in this two stress partitions are studied. As a result, the post-peak strength-softening mechanism dominated by the decrease of cohesion(decreased by 44.8% in the high-stress subarea, and 93.8% in the low-stress subarea) and the constant of frictional angle(the difference between peak and residual frictional angles in the high-stress subarea is 0.136°, but 0.468° in the low-stress subarea) is illuminated for the slip soils. By employing a weakening coefficient of cohesion, the back analysis method is adopted to study the critical strength of the reservoir landslide under different working conditions. Eventually, by considering the variation of slope stress and the softening-properties of the soils, the reasons why the critical strength is related with the working conditions are discussed, and their enlightening significance and engineering significance are also expounded.

关 键 词：环剪试验 力学特性 临滑强度 滑坡演化 反演 水库滑坡 

分 类 号：TU433[建筑科学—岩土工程]