Stability Evaluation And Landslide Surge Prediction Of Bajiaotian Landslide In Wushan County,Chongqing

With the water storage work in the Three Gorges Reservoir,the water level changes regularly between 145 m and 175 m,and the geological structure of the slopes in the riverside is complicated.And the river water caused the material composition,seepage and stress of the slope changed of the slopes,lesd to the original state changed on riverside,which resulted the geological disasters developed.The Yangtze River runs through Wushan County,located at the northeast boundary of Chongqing,where the water level changes reduce the stability of the slopes on both sides of the river and the landslide develops.When sliding at different scales,carrying great energy with difference,the instantaneous contact between the slope and the water surface generates energy transfer,which induces secondary disasters-landslide surge,which seriously endangers the safety of shipping,power station production and surrounding residents.Therefore,it is necessary to analyze the stability of the landslide along the Yangtze Riverr and predict the possible landslide surge.The paper takes the Bajiaotian landslide in Wushan County as the research object,analyzes the geological factors,deformation characteristics,factors and deformation mechanism in detail,and qualitatively evaluates the stability based on the data and deformation signs.According to the landslide engineering geological conditions,the Geo-studio software simulation was used to explore the effects of rainfall,water level changes and the coupling on the Yangtze River.The variation of the landslide seepage field and the change of stability were explored,and the landslide surge calculation formula was used to calculate the landslide and the secondary disaster was speculated.According to the main achievements of the research,there are:(1)By studying the engineering geological conditions,influencing factors and deformation characteristics of landslides,it is concluded that the main influencing factors of landslides are precipitation and water level fluctuations.The soil at the leading edge of the landslide has a large thickness,while the trailing edge is thin.The leading edge of the landslide is immersed in the water for a long time,and is determined as a traction landslide that slides along the base-volt interface.(2)The Seep/W and Slope/W unit simulations in Geo-studio finite element software are used to investigate the changes of seepage field and stability of landslides.The different precipitation strengths,water level fluctuations and their coupling effects on seepage and stability are analyzed comprehensively.Sexual effects have verified that rainfall and water level fluctuations are the main factors affecting landslides.(3)The seepage field of the landslide analyzes the coupling characteristics of the rising or falling water level with the same precipitation and the precipitation intensity,and the variation characteristics of the effluent field of the landslide with six different precipitation strengths(145m stable water level).The fluctuation of water level and precipitation are accompanied by the change of seepage field inside and outside the slope,which lead to the variation of the internal force of the slope is complicated,and the hydrodynamic pressure isformed;while the hydrostatic pressure is relatively simple when the water level is stabilized.(4)The simulation results of landslide stability show that the stability of the sloping field landslide decreases with the drop of the water level,and increases with the rise of the water level.In a word,the stability of the high water level is higher than the low water level.It is assumed that the six different rainfall intensity effects are the same time when in the low stability 145 m water level.The greater rainfall intensity,with the greater difference in pore water pressure reduction,and conclude that the stability of the landslide decreases with the increase of rainfall intensity.When coupling,the rainfall is assumed to be 450 mm,and the rainfall intensity of 45mm/d and 90mm/d is determined.The longer the duration or the greater the intensity of the precipitation,the greater the decrease in stability.The comprehensive shows that precipitation has a greater impact on the stability of landslide than water level changes.(5)According to the geological conditions and form of landslide engineering,predict the landslide surge by Yinkunlong's series of calculation formulas when the landslide slip into the Yangtze River in the 145 m and 175 m stable water level.The research shows that the rate of swell height reduction is first and then slower,within 10 km of the upper and lower reaches of the landslide.