| In the process of water storage in XiLuoDu Reservoir Area,a large number of bank slopes have been deformed and destroyed.Among them,the Qinggangping giant landslide is one of the most typical landslides revived under the action of reservoir water.The landslide was revived on April 24,2014.Nearly 3 million cubic metres of the deposits slipped into the Jinsha River,destroying a large number of houses,highways,water cellars and water pipes,which seriously threatened the lives and property of local residents.On the basis of on-the-spot investigation and collection of deformation and failure characteristics of the slope body in different time periods from before and after impoundment to before and after the revival of the landslide in the reservoir area,combined with actual displacement monitoring data of the slope body and deformation monitoring data of the slope body by InSAR,the physical and mechanical characteristics of the surface deposit body of the Qinggangping landslide were obtained by indoor and outdoor experiments,and the deformation and failure characteristics and evolution of the Qinggangping landslide were described in detail.Secondly,QUAKE/W and SLOPE/W are used to simulate the impact of Rainfall and Yongshan earthquake on the stability of Qinggangping landslide on April 5,2014.Then SEEP/W and SLOPE/W are used to simulate the impact of reservoir water fluctuation on the stability of the slope,and the revival mechanism of Qinggangping landslide is analyzed in depth.Finally,FLAC3D is used to simulate the change of slope displacement and stability during the rising and falling of reservoir water at540m~600m elevation in the later stage,and the deformation evolution trend of Qinggangping landslide is analyzed.Finally,the following conclusions are drawn:(1)Qinggangping landslide is a giant ancient landslide,which has been sliding many times in history.The surface of the landslide body is diluvium and basalt-dominated gravel layer,which distributes on Qinggangping platform with a thickness of 6.06~73.50m;the following is mudstone-dominated landslide accumulation with a thickness of 37.73~220.00m;the structure of the slip zone is compact,with a thickness of 1.10~5.33m,and is very compact mudstone debris,angle and angle.Gravel with mud;Sliding bed is Silurian shale.(2)The strong deformation area of Qinggangping landslide covers the area below the foot of the central steep slope(940m elevation);the area above the steep slope to the rear edge of the Qinggangping landslide is the weak deformation area,with the passage of time,the strong deformation area gradually moves to the upper part of the steep slope.Under the action of reservoir water,the front reactivating body is located in the middle of the strong deformation zone,with a slope of about 450m,a transverse width of about 300m,a sliding body thickness of 8.5~35m,a volume of about 3 million cubic meters,a sliding body of 8.5~35m,and a sliding belt of0.2~0.3m thick with gravelly clay and a sliding bed of gravelly clay.(3)The indoor and outdoor tests show that:(1)the porosity of the surface deposit of Qinggangping landslide is 0.69,the structure is dense and the overall gradation is good;the average permeability coefficient is 6.94×10-2cm/s,which is a medium-strong permeable medium.(2)The clay mineral content of gravel-bearing breccia clay in slope body is low,and the mineral content of water-soluble clay is low.Most of them are slightly soluble and insoluble minerals,and the influence of water on mineral composition is limited.(3)There is a relationship between shear strength index and water content of soil as follows:c=0.0417?~2-2.92?+68.86,?=0.494?+37.12.(4)The relationship between the shear strength index and the number of wet-dry cycles is as follows:c=0.00457n2-0.367n+27.0486,?=-0.166n+26.78.(4)Before impoundment,the Qinggangping landslide was in a stable state,and the local deformation of the slope was mainly caused by rainfall and irrigation.After reservoir impoundment,the stability of frontal resurrection body fluctuates to a certain extent and decreases gradually as a whole.Previous rainfall and M5.3earthquake in Yongshan on April 5,2014 can promote the local revival of the front of Qinggangping landslide to some extent,but it only causes tension cracks in the local area of the slope,so as not to cause large-scale revival sliding.Compared with the chemical and physical interaction between water and rock after water encounter,the reservoir water in the later stage is produced during the process of rapid decline from560m(0.8m/d)to 540m.Mechanical action(seepage erosion)is the direct cause of the revival of the front of Qinggangping landslide.(5)When the reservoir water level is stable at 540m and 600m elevation,the Qinggangping landslide is stable as a whole.Tension cracks occur only in the upper part of the mega-boulder upstream and downstream at 640~690m elevation above the fluctuation zone,and the width(displacement)of the cracks is 0.1~12.24cm.(6)The numerical simulation results show that under different wetting and drying cycles,the deformation parts of the slope mainly concentrate on the front,left and rear edges of the Qinggangping landslide which has been revived,and extend back to the high-rise of the steep wall at the rear edge of the strong deformation area at about 930m.The displacements are concentrated in the upper part of the giant rocks at 640-690m elevation.With the increase of dry-wet cycle number n,the deformation cracks of slope accumulation gradually increase and the stability coefficient decreases.When n=35,the accumulation body in the 780~930 m elevation range above the ebb-flow zone and the centralized position on the mega-block stones will slide,and the Qinggangping landslide will revive again.According to the frequency of the reservoir water cycle once a year,the landslide will slide again after about 35 years from April 24,2014,that is,around 2049.If the reservoir water rises and falls more frequently,coupled with rainfall,earthquakes and human engineering activities.The impact of this process will be advanced. |
PDF Full Text Request