摘要
砾石在古滑坡滑带土中广泛存在,确定含砾滑带土的启动强度是古滑坡稳定性评价和灾害防范的关键。以2018年甘肃舟曲县江顶崖古滑坡复活事件为例,基于试验测试和反演分析方法,研究了含砾滑带土的复活启动强度。结果表明:(1)长距离剪切后,滑带土中的胶结作用已逐渐丧失,其残余抗剪强度主要由土颗粒之间的滑动摩擦阻力和咬合作用所导致,砾石含量较高时土颗粒之间的力较强,因而其残余强度也相对较大。剪切面摩擦系数与粗糙度呈正线性相关性,砾石改变了剪切面的粗糙度,使剪切面摩擦阻力增大,导致其残余强度增大。(2)含砾滑带土的残余内摩擦角同时受黏粒含量和砾石含量的控制,与黏土质滑带土主要受黏粒含量控制的机制具有明显差异,建议采用砾石含量与黏粒含量之比作为估算含砾滑带土残余内摩擦角的指标。(3)古滑坡复活启动强度一般大于残余强度但略小于恢复强度,复活启动前的滑带土强度已经由恢复强度向残余强度逐渐衰减,此时古滑坡整体上处于蠕滑状态,在外力作用下,滑带土强度易发生急剧衰减,从而诱发古滑坡加速滑动。
Gravels are widely found in the sliding zone soils(SZS)of ancient landslides.It is the key to determine the mobilized strength of SZS with gravels for the stability evaluation and prevention of ancient landslides.Taking the reactivation of Jiangdingya ancient landslide in Zhouqu County,Gansu Province in 2018 as an example,the mobilized strength of SZS with gravels was studied based on the test and back analysis.The results suggested that:(1)after long-distance shearing,the cementation in the SZS has been gradually lost,and the residual strength is mainly controlled by the sliding frictional resistance and occlusion between the soil particles.When the gravel content is higher,the interaction force between the soil particles is stronger,so the residual strength is relatively larger.There is a positive linear correlation between the friction coefficient and roughness of the shear surface.The gravel changes the roughness of the shear surface,which increases the friction resistance and leads to the increase of its residual strength.(2)The statistical analysis showed that theφr of SZS with gravels is controlled by both clay and gravel content,which is significantly different from the mechanism that theφr of SZS without gravels is mainly controlled by clay content.It is suggested that the ratio of gravel content to clay content should be used as an index to estimate theφr of SZS with gravels.(3)The mobilized strength of ancient landslides is generally greater than the residual strength,but slightly less than the recovery strength.Before reactivation,the strength of SZS has gradually attenuated from the recovery strength to the residual strength.At this time,the ancient landslide is in the creeping state as a whole.Under the action of external forces,the strength of SZS tends to decay sharply,which induces the accelerated sliding of the ancient landslide.
作者
任三绍
张永双
徐能雄
吴瑞安
刘筱怡
REN San-shao;ZHANG Yong-shuang;XU Neng-xiong;WU Rui-an;LIU Xiao-yi(Institute of Hydrogeology and Environmental Geology,Chinese Academy of Geological Sciences,Shijiazhuang,Hebei 050061,China;School of Engineering and Technology,China University of Geosciences,Beijing 100083,China;Key Laboratory of Quaternary Chronology and Hydrological Environmental Evolution,China Geological Survey,Shijiazhuang,Hebei 050061,China;Institute of Geomechanics,Chinese Academy of Geological Sciences,Beijing 100081,China)
出处
《岩土力学》
EI
CAS
CSCD
北大核心
2021年第3期863-873,881,共12页
Rock and Soil Mechanics
基金
国家自然科学基金重点项目(No.41731287)
国家自然科学基金重大专项项目(No.41941017)。
关键词
滑坡复活
含砾滑带土
残余强度
强度恢复
启动强度
landslide reactivation
sliding zone soils with gravels
residual strength
strength recovery
mobilized strength
