湘西陈溪峪滑坡变形机理及稳定性评价

浅层滑坡在我国广泛分布，但在区域范围内分布规律性较差，且具有突发性、隐蔽性和破坏性强等特点。湘西武陵山区地质条件复杂、降雨丰沛、人类工程活动强烈，突发性地质灾害频发，尤以降雨诱发的浅层滑坡为主。文章以湘西地区慈利县陈溪峪滑坡为例，开展了降雨量、基质吸力、地下水位和地表变形等的监测；结合滑坡的现场调查及监测成果，分析滑坡的形成条件和变形机理；在此基础上，考虑基质吸力对边坡稳定性的贡献，将强度折减有限元法推广到非饱和土边坡，计算得到了不同降雨工况下滑坡稳定性。结果表明:当强降雨降落到滑坡体上时，坡内基质吸力值均迅速减小，直至一定值后（9.5 kPa左右）不再变化；坡内地下水位受季节性降雨影响显著，短时强降雨引起地下水变化幅度不如长时间降雨对地下水位造成的影响大；陈溪峪滑坡的地质力学成因为蠕滑推移式土质滑坡，运动形式为沿基覆界面的浅层滑坡；短时强降雨是诱发滑坡变形的最关键因素。陈溪峪滑坡在持续降雨条件下的降雨量预警值约为280 mm，在短时强降雨条件下的降雨强度预警值约为240 mm/d。

A study of deformation mechanism and stability evaluation of the Chenxiyu landslide in western Hunan

Shallow landslide hazards widely occur in China. The distribution regularity of this type of landslide areas is poor, and it is characterized by suddenness, concealment and destructiveness. In the Wuling Mountains, geological conditions are complex, rainfall is abundant, human engineering activities are intense, and sudden geological disasters occur frequently, especially the shallow landslides induced by rainfall. The Chenxiyu landslide in Cili county of western Hunan is taken as an example, and monitoring of rainfall, matric suction, groundwater levels and surface deformation is carried out. Combined with field investigation and monitoring results of the landslide, the formation conditions and deformation mechanism of the landslide are carried out. By considering the contribution of matrix suction to slope stability, the strength reduction finite element method is extended to the unsaturated soil slope, and the stability of landslide stability under different rainfall conditions is calculated. The results show that when heavy rainfall falls on the landslide, the matrix suction value in the slope decreases rapidly and does not change after a certain value (about 9.5 kPa). The groundwater level in the slope is significantly affected by seasonal rainfall and the groundwater is caused by short-term heavy rainfall. The geomechanics of the Chenxiyu landslide is due to the creeping-type soil landslide, and the movement form is a shallow landslide along the base-covered interface. Short-term heavy rainfall is the most critical factor inducing the landslide deformation. The rainfall warning value of the Chenxiyu landslide under continuous rainfall is about 280 mm, and the warning value of rainfall intensity under short-term heavy rainfall is about 240 mm/d.