Abstract: The field geological exploration and survey are used to determine the form and property of Liujiaao loess landslide; in the western mountainous area of Henan province in-situ test and laboratory test are used to determine the influence factors and weakening law of strength of sliding zone soil; field monitoring are used to determine sliding depth. The activity history, formation causes, range and influence factors of Liujiaao loess landslide are analysed based on investigation and tests. Survey and analysis results show that, the sliding mechanism of Liujiaao loess landslide can be summarized as local ancient landslide revives caused by excavation of cutting and rainfall. For ancient landslide, the loess mass structure is relatively loose and shear strength is poor. When the front soil of ancient landslide is cut, ancient landslide loses the front supporting and retaining, and then the front of ancient landslide slips and failures along the sliding zone of interface of loess layer and gravel layer under the interaction of gravity stress and groundwater. According to the analysis of ancient landslide revival, Liujiaao loess landslide is pull-type landslide. After the front of ancient landslide sliding, the latter can slide successively and the crack develops in depth.

Key words: loess landslide, in-situ direct shear test, field monitoring, sliding failure mechanism, sliding zone soil, stability