| The Niulanxi landslide is located in Xinglong Township,Sinan County,Tongren City,Guizhou Province.In June 2014,after continuous rainfall,various parts of the slope were cracked and deformed to varying degrees.The landslide was located on the steep slope on the south bank of the Longdi River,and the potential sliding surface was located The interface between the strongly weathered shale and the moderately weathered shale in the Ordovician strata can also be considered as the contact surface between soil and rock.The scale of the landslide is initially estimated to be 400,000 cubic meters and the volume is relatively large.This landslide is more likely to lose stability and slip under continuous rainfall conditions.Once it slips,it will cause greater property losses and casualties.Therefore,studying this landslide is of great significance to the prevention and prevention of landslides.Based on a detailed investigation of the basic geological conditions,basic morphological characteristics and deformation characteristics of the landslide,this paper uses FLAC3D software and MASSFLOW software to perform numerical simulations to study the deformation and failure mechanism of the landslide induced by rainfall and the accumulation characteristics after the landslide failure.The main results achieved are as follows:The main materials of the Niulanxi landslide are Quaternary residual slope gravel soil,cultivated soil,and Ordovician strongly weathered mud shale.The lithology of the slide bed is Ordovician middle weathered mud shale,and the rock mass is relatively complete.And the stability is good,so the landslide is a rock-soil mixed landslide,and because the landslide landslide accumulation structure is loose,the landslide has the basic characteristics of an accumulation landslide.The landslide is located in a section of steep slope,the slope direction is 89°,the natural slope angle is20°?35°,and the height difference is greater than 250m.The main sliding direction of the landslide is 78°,the slope of the landslide body is about 325m,the average width is about 165m,the surface area of the sliding body is about 53625m~2,the average thickness of the sliding body is about 7.5m,and the volume is about 402,200m~3.Because the landslide may slide under continuous rainfall conditions,and in the Niulanxi landslide,the small landslide formed by the steep ridge in the middle of the landslide has a great influence on the entire landslide.This small landslide will slide first under continuous rainfall conditions.Because it is a traction sliding,it will drag the rock and soil behind it,causing a large number of sliding bodies to squeeze downwards to push the lower sliding body to slide and cause the entire landslide to lose stability and damage.The relatively smooth part of the lower part of the slide is the anti-slip section of the Niulanxi landslide or can be called a key block,which largely determines the ultimate stability of the Niulanxi landslide?The deformation characteristics of the landslide are mainly manifested as the trailing edge tensile fracture and the large number of tensile fractures and shear fractures in the middle and upper part of the landslide body.The maximum fall height is 2m.The walls of many houses were cracked,and some roads were interrupted due to landslide deformation.The slope of the landslide front has a small thickness,occasionally a few tensile cracks are seen,and the front deformation is not obvious.The field investigation did not find obvious front deformation,so it can only be inferred that the landslide front is located at a steep ridge in the lower part of the slope.The FLAC3D finite difference method is used to study the deformation and failure process of the Niulanxi landslide under continuous rainfall conditions.In the initial stage,the landslide's trailing edge and central ridges have obvious displacement,and tensile cracks are formed at the trailing edge and the middle.There is a small amount of deformation at the toe of the steep ridges,and a few tensile cracks begin to form;then the landslide's trailing edge and central ridges appear Partially slid,and the slumped part produced a squeezing effect on the remaining part;at this time,the potential sliding surface penetrated in the middle part and continued to develop towards the toe of the slope;finally,the rock and soil mass in the middle of the landslide slipped on a large scale,and the toe of the slope was potentially slipped The upward extension is connected with the sliding surface in the middle,and the sliding surface of the landslide is completely formed.At this time,the landslide is unstable and damaged.Use MASSFLOW to simulate the sliding range and accumulation characteristics of the landslide after sliding.The landslide starts at a faster speed,and then decelerates for a relatively long time until it stops.Calculating the sliding range of different supervoid water pressure coefficients,the results are approximately the same.The landslide eventually slid to the right bank of the Longdi River,and there is a possibility of slipping into the Longdi River. |
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