Study On The Characteristics Of Gravitational Slope Deformation And Critical Elevation Threshold In Xinmo Region

The gravitational slope deformation is strongly controlled by the rock mass structural plane and the slope free surface.It usually occurs in the high mountain canyon area of the orogenic belt.Once it is converted into a large-scale landslide and collapse,it will cause devastating damage.Songpinggou in the Xinmo region of Maoxian is a tributary of the Minjiang River.Its topography is steep and the regional structure is active,resulting in typical gravitational slope deformation and frequent occurrence of large landslides.In 2017,the Xinmo landslide in this area started at a high position on the slope.The high-speed movement reached the bottom of the valley and buried the Xinmo Village at the bottom,causing huge loss of life and property.At present,there have been many research and analysis results for the Xinmo landslide,but the mechanism of the landslide formation developed from the gravitational slope deformation is still insufficiently understood,and the distribution and development characteristics of the gravitational slope deformation in the adjacent area are also unclear.Based on the terrain analysis of GIS combined with field refined geological survey,the research was carried out on the gravitational slope deformation of Xinmo landslide and its adjacent areas,and the structural characteristics,formation patterns and countermeasures of gravitational slope deformation in Xinmo were analyzed.On this basis,in order to better prevent the geological disasters developed by gravitational deformation,it is urgent to effectively determine the gravitational slope deformation exists on the elevation position of the slope.Using viscoelastic mechanics,the critical elevation threshold of slope gravity deformation in the area was studied.Mainly include the following aspects:(1)In this paper,the GIS method was used to interpret the DEM images of Xinmo region,and it was found that 7 large-scale landslides in Xinmo region all located on the left bank of Songpinggou River,with obvious location characteristics.(2)The west and east areas of the Xinmo landslide and the slope where the Xinmo landslide is occured were investigated respectively.The topography,stratigraphic lithology and geological structure in the Xinmo region were investigated.The terrain features was analyzed,and it was found that the gravitational deformation folds as structural features widely exists in Xinmo region.On this basis,the formation mode of gravitational slope deformation in Xinmo region and the promoting effect of Xinmo landslide were analyzed.(3)Based on the theory of viscoelastic mechanics and composite materials,the equivalent elastic modulus of the layered rock mass in the study area was calculated to be 42.50 GPa,and the critical instability load of the rock layer was calculated to be32.04 MPa.The critical elevation threshold of gravitational deformation fold in the Xinmo area was determined to be 890.01m?1335.01 m away from the top of the slope,which was verified with the elevation data of gravitational deformation fold in the area,providing support for the distribution research and disaster prevention of gravitational deformation fold in Xinmo area.