| Shanyang County is located in the southwest of Shangluo City,Shaanxi Province,on the south slope of qinling mountains,where the geological environment is poor and geological disasters are developed.The accumulation landslide is the most developed,the most widely distributed and the most harmful geological disaster type in the study area,and it has the typical characteristics of rainfall landslide.Therefore,it is of great significance for the prevention and control of local geological disasters to study the development characteristics of accumulation landslides and the formation and evolution mechanism of accumulation landslides induced by rainfall in Shanyang County.Based on the investigation data of geological hazards in Shanyang County,this paper summarizes the structural characteristics and development law of the accumulation landslide in Shanyang County through statistical analysis and field verification.On this basis,a representative accumulation landslide is generalized as the prototype of physical model test of rainfall-induced accumulation landslide.By carrying out the model test to simulate the deformation and failure process,the mechanism of formation and evolution of accumulative landslide induced by rainfall is revealed.The research work and results are as follows:(1)The statistical analysis of the structural characteristics of accumulation landslide in shanyang county shows that: the accumulation landslides in the study area are mainly small and shallow landslides;the aspect ratio of the landslide plane is mainly longitudinal and isometric,the sliding surface is mainly soil-rock interface,the longitudinal morphological features of the sliding surface are polygonal and curved,and the sliding surface of the main sliding section is linear,its inclination angle is mostly between 20°~40°;the material of the sliding body is mainly composed of gravel clay,the material of the sliding zone is mainly residual soil.(2)According to the law of development and distribution of accumulation landslide in shanyang county,the analysis shows that: the formation of landslides in the study area is the result of the interaction of environmental factors and induced factors,The environmental factors are:(1)formation lithology;(2)topography;(3)geological structure and neotectonic movement,induced factors include:(1)rainfall;(2)human engineering activities.(3)Based on the similarity theory,the size similarity ratio of the model test is determined to be 66.7 while considered the structural characteristics of the accumulation landslide in the study area and the current experimental conditions.The similar materials in the experiment are divided into three parts: using masonry stone and plastering surface to simulate the sliding bed,choosing four layers of polyethylene film as sliding surface similar materials,and using the ratio of barite powder: fine sand: double flying powder: talcum powder: water = 3:4:1:1 to prepare sliding body similar materials.(4)Through the qualitative analysis of the pore water pressure change process and the quantitative analysis of the stability of the slope changing with the pore water pressure during the model test,combined with the deformation and failure characteristics of the slope,the formation and evolution mechanism of the rainfall induced accumulation landslide in the model test is analyzed as follows: the rainfall caused the groundwater level of the slope to rise and the stability of the landslide was reduced,which led to the deformation and sag of the slope,and then the trailing edge was cracked,and the overall slope of the slope was destroyed.(5)Based on the structural characteristics,formation conditions and landslide model test results,the formation and evolution mechanism of accumulation landslide in shanyang county is concluded as follows: the frequent rainfall in the study area causes the rainwater to converge at the soil-rock interface of the deposit landslide,causes the change of groundwater level in the landslide body,and reduces the stability of the landslide body.At the same time,because the accumulation landslides in the study area are mostly developed in the gentle slope zone between the upper and lower steep slopes,which has good empty conditions,leading to deformation and failure at the foot of the landslide,then tension cracks appear at the back edge of the slope,cracks develop through,and finally the whole landslide slides downward along the crack surface through the back edge.The deformation and failure process of this type of landslide is: rainfall? crack at the foot of the slope? crack development and penetration,overall slippage of the slope foot? trailing edge cracking? crack development and penetration? Slope overall slip damage. |
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