三峡库区云阳县向城小学滑坡自2011年来一直持续变形,其稳定性及变形发展趋势密切关系到坡体上居民的生命财产和长江航道的安全.基于现场调查和工程地质勘察,详细介绍了滑坡发育特征;采用X射线衍射和电镜扫描分析了泥岩软弱夹层的矿物组分和微观结构,并结合室内试验探究其膨胀性和崩解性;从岩体建造特征、构造影响以及外动力作用等方面分析了滑坡的变形失稳机制.研究表明:向城小学滑坡为软硬互层结构的岩质滑坡,其稳定性主要受泥岩演化而成的软弱夹层控制,其变形破坏模式为蠕滑-拉裂-剪断式;软弱夹层主要粘土矿物为伊利石和伊利石-蒙脱石混层矿物,具较好的亲水性和一定的不稳定性,崩解性较好,微观结构以片状结构为主,部分呈层状定向排列;构造作用和岩体的建造特征对滑坡的形成演化起到控制性作用,降雨和库水位升降变化的耦合作用对滑坡变形发展起到促进作用.%Continuous deformation have occurred on Xiangcheng elementary school landslide since 2011,whose stability development trend is closely related to the safety of the lives and properties of the residents on the slope.Based on detailed landslide investigation and engineering exploration,the special geologic environment and characteristics of the landslide are examined.And we analyzed the mineral composition and microstructure of mudstone weak intercalations by XRD and SEM,and also test the disintegration and expansibility of silty mudstone in the laboratory.The deformation and failure mechanism was studied from many aspects including rock mass formation,geological structure,and external dynamic function.Research shows that Xiangcheng elementary school landslide is a bedding rockslide developing in soft-hard alternant strata.The stability of the landslide is mainly controlled by weak interlayer which is evolved from mudstone.The formation and failure model of the slope is creeprip-cut off.The main clay minerals of weak interlayer are illite and illite-montmorillonite mixed layer mineral with good hydrophilicity and instability,and the disintegration of the clay minerals performs good.The microstructure of the main clay minerals is given priority to lamellar structure,part of them present layered orientation arrangement.The formation and evolution of the landslide are controlled by combined effects including rock mass formation features,geological structure influences,the coupling effects of rainfall and water level variation play an important role on promoting the deformation of the landslide.These results can contribute to deeply understand the deformation and failure mechanism of similar landslides,and guide the disaster prevention and mitigation engineering.
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