Study On Formation Mechanism And Deformation And Destruction Of Landslide Group In Zhonglu Township Of Danba County

Danba County Zhonglu Township landslide group is located in Zhonglu Township of Xiaojin River left bank slope,the basic coastal slope direction,a total of nine large and small landslides facing to Xiaojin River which distribute on the Shore slope.In recent years,landslide deformation and damage intensified,resulting in the road fault,landslide near the housing cracking,farmland sliding damage,and a large number of collapse,Zhonglu people's lives and property security to form a great hidden danger,the normal traffic on the highway Causing a serious threat,if the overall decline in landslides and even plug the Xiaojin River,the consequences could be disastrous.In this paper,the spatial distribution,development characteristics,formation causes and sliding modes of landslide group are analyzed by field investigation.Then,the typical landslide in the area is studied in detail,and their deformation and failure mechanism is determined.The deformation and failure mechanism of typical landslide is simulated by Flac3D numerical simulation software.Finally,the stability of typical landslide is calculated by unbalanced thrust method.The main contents and achievements of this paper are as follows:(1)According to the field survey results and the related literature,it is concluded that the landslides group of Zhonglu have two developmental models on the plate and the lower plate of the F1 fault.The number of landslides on the F1 fault is more,and the deformation and failure characteristics are small.The number of landslides located under the F1 fault is small,the sliding mode is the push type,and the deformation and damage characteristics are obvious.By analyzing the various internal and external causes of landslide formation,it is concluded that the failure mode of the slope is Rock and soil below F1 fault sliding along the layer,and then Rock and soil on the F1 fault slump be causing Lack of support.The upper fault landslide developed in the back of the bedrock cliff,by the bottom of the bedrock instability or other factors induced sliding,The below fault landslide is mainly the accumulation body formed by the early bank slope collapse,which is induced by external factors.(2)The landslides located below the F1 fault slides have slides in recent years,one of them landslides have slipped as a whole.Based on the study of the typical landslide,the results show that Slope foot destroyed by the excavation of the highway in 2012,and the heavy rainfall caused the partial resurrection of the Boselong landslide.The numerical simulation results also It is confirmed that this kind of judgment shows that the landslide is mainly slippery before the excavation of the slope,and the landslide in the heavy rain after the excavation is sliding.(3)Located on the F1 fault of the landslide less harmful,but in recent years has also increased the deformation.Based on the study of the typical landslide Sanjiazhai landslide,it is considered that the deformation of the main strata of the Sanjiazhai landslide is aggravated due to the invasion of the leading edge and the heavy rain,but the deformation characteristics of the weak deformation zone in the back of the landslide are not obvious.The results of the Flac3D numerical simulation show that under the condition,the displacement in the main slip direction of the leading edge is larger,and the trailing edge is dominated by the vertical displacement,which is the same as the fault deformation.This is consistent with the actual situation of the landslide.(4)The results of quantitative analysis of two typical landslides using unbalanced thrust method show that the Boselong landslide is basically stable under natural conditions and is less stable under heavy rain and earthquake conditions.Sanjiazhai landslide in the natural conditions for the steady state,heavy rain and earthquake conditions for the stability of?less stable,but its leading edge in the rain conditions for the instability,the earthquake state is less stable.Therefore,the stability of landslides of the upper Fl fault is better than that below the F1 fault.