Comparative Study On The Stability Of Typical Rock Landslid E And Accumulation Landslide In T₂b² Strata In Three Gorges Reservoir Area

A large number of rock and accumulation landslides lie in the Badong Group in Three Gorges Reservoir Area.To raise the falling rate of reservoir water level,finding out changes of landslide stability and determining threshold of falling rate are the primary tasks.The Zhaoshuling landslide,the Dongpo landslide and the Jianyugou landslide are developed in the Badong strata(T₂b²).In this paper,first we summarise the current modification of Zhaoshuling landslide by analysising the monitoring data from January 2006 to May 2014.Then simulate the seepage field of three landslides under conditions of different falling rates of the reservoir water level and short-term heavy rainfall by two-dimensional finite element software Geo Studio2007.We respectively use Morgenstern-Price method and Imbalance Thrust method to compute the stability of landslides under different conditions,and discuss the difference of stability tendency between rock landslide and accumulation landslide.Last,establish quasi-3d geological model for Zhaoshuling landslide to predict the behavior of landslide under adverse conditions by FLAC3D.The main results are as follows:(1)Monitoring of Zhaoshuling landslide shows that less response to water level fluctuation and heavy rainfall is occured.Surface monitoring results show that the water level is now under landslide dispatch slightly larger than the front portion of the cumulative amount of displacement in the rear,the average cumulative displacements are respectively 62mm,37mm,27mm from 2006 to 2011.Deep displacement monitoring shows that relatively stable deep landslide,displacement do not change.Groundwater level monitoring showed the front of the water table by the landslide of water level fluctuations significantly,synchronization is better,obviously affected by rainfall in Central.(2)Short heavy rainfall and water level fluctuation will cause Zhaoshuling landslide stability decreased,but the range is slightly.Reservoir water level rise will increase landslide stability,stability was raised to a certain extent after 175m fall,175-159m slow decline slightly improved phase stability of landslide,but the rapid decline in the 159-145m phase stability over decline,and with the drop increase speed and amplitude also increases the rate of decline.(3)The fluctuation which Dongpo landslide responses to short-term heavy rainfall and reservoir water level is obvious,prone to instability.After the discovery deceleration by simulating different Dongpo landslide No storm conditions slow down the water level threshold 1.2m/d,adding storm conditions to 1m/d.(4)The Jianyugou landslide has a good stability,the reservoir water level fluctuations and short-term heavy rainfall is not obvious.Because the leading edge elevation of is 156m and the base taro Landslide landslide is thin,long and sloping slow.(5)T₂b² landslide slope has large bedrock permeability coefficient and good groundwater discharging.So the reservoir water level fluctuations and short-term heavy rainfall has better tolerance,better stability,the reservoir water level is much room to withstand deceleration.T₂b² debris landslide slope permeability coefficient is small and has poor drainage groundwater.Thus the reservoir water level fluctuations and short-term heavy rainfall has obvious response,deformation and failure-prone.