Study On Deformation Mechanism And Stability Of Jiuxianping Landslide In The Three Gorges Reservoir Area

The deformation of Jiuxianping Landslide in the Three Gorges Reservoir area has intensified since the Three Gorges Reservoir was impounded,which poses a huge menace of the residents,highways,shipyards,ship repair yards,driving schools and the Yangtze River shipping on the slope.Construction and regional disaster prevention are of great significance.Through multiple on-site surveys and visits,combined with previous survey data and previous research results,the deformation characteristics of the landslide have been basically identified,and through monitoring data analysis,centrifuge physical simulation,FLAC^3D numerical simulation and Geo-studio The main influencing factors of the landslide,the deformation mechanism of the landslide,the stability of the landslide and the deformation evolution trend of the landslide were studied.The article finally reached the following main conclusions:1)The Jiuxianping landslide is a very large rocky old landslide.Since the Three Gorges Reservoir impounded,the slope has undergone periodic creep deformation.?2?Based on the comparative analysis of slope body deformation monitoring data,it is clear that reservoir water rise and fall is the leading factor of landslide deformation.The impact of the first water storage on the stability of the slope body is more significant.In the subsequent periodic operation of the reservoir,the deformation shows a decreasing trend.Combining the relationship between the changes of reservoir water and displacement,the periodic deformation of landslides is divided into three stages:reservoir water level rise and weak stage of high water level slope deformation?reservoir water decline slope intensified stage deformation?low water level slope deceleration deformation stage.?3?The large-scale geotechnical centrifuge experiment was used to simulate the whole process of the deformation of the landslide of the reservoir water up and down several times,and the influence of the hydrodynamic pressure,hydrostatic pressure and floating force on the deformation of the landslide was clarified during the reservoir water up and down process.In the rising stage of the reservoir water,the internal water level of the slope body lags behind the reservoir water.At this time,the increase of the dynamic water pressure,static water pressure and buoyancy force in the sliding section are all conducive to the stability of the slope body;Decrease,the internal water level of the slope body lags behind the reservoir water,and generates dynamic water pressure pointing outside the slope.The weight of the rock and soil body in the falling section changes from floating weight to natural weight.The increase of the overall sliding force of the slope body is not conducive to the stability of the landslide;Increasing the rate of rise and fall of the reservoir water,the internal water level of the slope body lags behind the reservoir water level,and the slope body deformation is further aggravated.The dynamic water pressure plays a controlling role in the whole process of water rise and fall.?4?The comprehensive landslide geological environment data,deformation monitoring results and centrifuge physical simulation test results summarize the deformation mechanism of Jiuxianping landslide as follows:the top slope and the gentle leading edge reverse warping terrain control the landslide deformation.The dynamic water pressure has the most significant influence on the stability of the landslide during the periodic rise and fall of the reservoir water,but the deformation of the landslide is also restricted by the buoyancy force and the static water pressure of the leading edge,which results in the periodic deformation of the landslide.?5?The numerical simulation of Flac3D shows that the fluctuation of reservoir water has a significant effect on the stability of slope body,and the rainfall has a certain effect on the stability of slope body,but it is smaller than that of reservoir water.Rising reservoir water and high water level are conducive to body stability,while falling reservoir water and rainfall are not conducive to slope body stability.?6?Geo-studio predicts the evolution trend of landslide deformation.The prediction results show that the effect of water level rise and fall on the stress field of the slope body is obvious,but with the adjustment of the reservoir water to the landslide's own stress field,the reservoir water level changes affect the landslide deformation The effect of the impact will continue to weaken,and although the cumulative deformation of the landslide continues to increase,the amount of periodic deformation will continue to decrease and eventually stabilize.