Revival Mechanism And Risk Assessment Of Old Landslide In Bridge Area

With the highway extends to complex terrain conditions in the western region, a series of different scale landslides occur frequently, so some bridges across the landslide area is unavoidable. Landslide disaster threat to nearby residents to safety of life and property, also to the traffic safety operation.So counter the landslide in the bridge area, this thesis theoretically analyzes the characteristics of bridge foundation bearing force and the interaction of bridge foundation-soil on the slope area, analyzes the difference of bridge foundation bearing force between slop and flat area. In addition, analyzes the factors which cause landslide in detail. Then, this thesis base on the Zongshudang Landslide simulate starting mechanism, the selection of pile position,the process of deformation by finite element analysis. Finally, assesses risk of Zongshudang Landslide by Monte Carlo Method and Analytic Hierarchy Process, obtain the risk level of Zongshudang Landslide. This thesis draws the following conclusion:(1) The force state of bridge foundation on slope is different from plain areas: bridge foundation on slope play a double duty of bearing upper structure load and sliding force.(2) Because of free surface on the slope side, the soil around the bridge foundation is no longer semi infinite space, so exit "steep effect" phenomenon:the resistance force of the foundation is weakened.(3) There are many factors of cause landslide can be divided into two categories: external factors(topography, layer construction, meteorology and hydrology, earthquakes,human activities) and internal factors(soil structure of landslide,surface form of slope), these factors led to the slide slope.(4) Starting mechanism of Zongshudang Landslide is draw type, due to forepart of slope excavation has caused the instability.(5) Base on the Zongshudang Landslide, when take piles supporting measure, piles should be set in the front of landslide can limit displacement of soil deformation.(6) Trough hazard analysis of Zongshudang Landslide get failure probability of it is 0.7785.Also, analyse vulnerability of population, housing, traffic facilities.(7) Based on the analysis of hazard and vulnerability, calculated value of the risk of Zongshudang Bridge Landslide and pointed out the disaster risk grade is III.