渗透作用下滑带细观结构演变特性  

Meso-structure evolution of the sliding zone under seepage conditions

作　　者：安鹏举 鲁莎[1] 唐辉明[1] 孙思璇 张子涵 缪明昊 An Pengju;Lu Sha;Tang Huiming;Sun Sixuan;Zhang Zihan;Liao Minghao(Faculty of Engineering,China University of Geosciences(Wuhan),Wuhan 430074,China)

机构地区：[1]中国地质大学(武汉)工程学院,武汉430074

出　　处：《地质科技通报》2022年第6期169-179,共11页Bulletin of Geological Science and Technology

基　　金：国家自然科学基金重大项目(42090054);国家自然科学基金项目(42107194)。

摘　　要：库岸滑坡受到库水升降作用影响,内部渗透压力会产生周期性的变化。动态渗透压力会导致滑带结构与强度产生劣化,进而影响滑坡整体稳定性。为揭示滑带在渗透作用下的结构演变特征,通过室内渗流试验结合CT扫描技术获取了黄土坡滑坡滑带在不同渗流条件下的细观结构特征,采用Avizo软件量化滑带细观结构参数,定量分析了不同渗透条件下滑带结构的演变规律。结果表明,滑带的渗透系数随渗流时长的增加而呈指数形式下降,且水力梯度越大最终试样的渗透系数越小;连续的CT重构图像显示渗流过程中部分黏土团聚体发生解体,大孔隙被附近的细颗粒逐渐充填,试样结构的宏观均一性增强;统计数据表明滑带土的表观孔隙率由5%下降到了1%,等效直径小于80μm的孔隙占比随渗流时长的增加而增多,而等效直径大于80μm的孔隙占比随渗流时长的增加而减少。结果证明周期性渗透作用会影响滑带内孔隙结构的分布特征,细观上表现为大孔隙被小颗粒充填,导致渗流通道变得细长而弯曲,孔隙的有效连通性被削弱,宏观上表现为渗透系数随渗流时长的增加而降低。Periodic fluctuations of reservoir water level lead to the variations in seepage stress inside landslide bodies.Dynamic seepage pressures can lead to deterioration in the structure and strength of the slide zone,which affects the stability of the landslide.To identify the effect of seepage on the pore structure of the slip zone,the seepage tests were performed.First,a seepage test apparatus was developed and combined with CT scanning technology to obtain the meso-structure of the sliding zone under different seepage conditions.Then,the changes in the structural parameters of the slip zone soils were quantified by Avizo software.Finally,the mechanism of the meso-structural evolution of the sliding zone under seepage was analyzed.The results show that the permeability coefficient of the sliding zone decreases exponentially with time,and a higher seepage pressure will lead to a smaller permeability coefficient of the sliding zone.Statistical data show that the apparent porosity of sliding zone soil decreases from 5%to 1%.The proportion of pores with an equivalent spherical diameter of less than 80μm increases with seepage time,while the proportion of pores with an equivalent spherical diameter greater than 80μm decreases with seepage time.The above results indicate that the large pores in the slip zone soils are filled with small particles during the seepage.Hence,the seepage channels become elongated and curved,and the effective connectivity of the pores is weakened.

关 键 词：渗透作用 滑带 细观结构 孔隙 黄土坡滑坡 

分 类 号：TU413.62[建筑科学—岩土工程]