| In recent years,with the intensification of tectonic movement and the expansion of engineering disturbance,many old landslides have appeared signs of revival.Landslide disaster is unpredictable and sudden,which is often accompanied by a large area of mountain collapse,which is easy to cause great damage to personnel and property.In our country,Tibetan Plateau and loess Plateau due to the effects of tectonic action,hydrological erosion and other geological actions,it has become an frequent area of natural disasters such as collapse,landslide,debris flow.The gullies in the region are developed and the terrain is steep.Under the action of the earthquake,the landslide accumulation body is disturbed and the slope is unstable,which produces great harm even more than the earthquake itself.Therefore,more and more attention has been paid to the research on the evolutionary mechanism of seismic landslide accumulation body.The landslide accumulation body of Shuiboxia is located on the left bank upstream of Shuiboxia Reservoir dam of Bailong River,which belongs to the super-large rock slope,and showed signs of overall activity during the Wenchuan earthquake.On the basis of existing data,the field geological survey of Shuiboxia landslide deposit body is carried out,the landform and landform of Shuiboxia landslide deposit body are identified and the engineering geological zoning is carried out,the slope structure characteristics of the landslide deposit body are revealed,the structural characteristics and seismic dynamic response of the landslide deposit body after the slide are studied by qualitative and quantitative analysis methods,and the deformation development process is analyzed.The main conclusions of this paper are as follows:(1)The Shuiboxia landslide accumulation body belongs to the West Qinling tectonic belt,which is rich in structural landforms and densely covered with high mountains and deep valleys.It is controlled by two large fault tectonic belts around it,resulting in broken rock structure.The front of the landslide accumulation body is adjacent to Bailong River,which is scoured and eroded by running water all year round.The length of the front and rear edges of the landslide accumulation body is 1063 m,the elevation difference is 610 m,and the overall slope is 15-45°.The upper part of the landslide deposit body is Quaternary deposit body with loose structure and argillaceous cement,while the lower part is interbedded with Silurian SLATE and phyllite.(2)Shuiboxia landslide accumulation body can be divided into landslide collapse area,debris migration area and debris accumulation area from top to bottom.According to the deformation characteristics of the upper sliding body,the upper sliding body is divided into five regions,including the main sliding body and the secondary sliding body.Gully and joint development in slope.According to the characteristics of tensile arc-shaped cracks at the rear edge,displacement shear cracks at the front edge of landslide accumulation body,and small collapse at the middle and lower part of landslide accumulation body after the Wenchuan earthquake in 2008,the overall deformation of landslide body is mainly the arm-chair landform formed by sliding at the rear edge and the soil slippery at the front edge,which is relatively stable at present.In the pause phase of intermittent slow sliding.(3)FLAC3D software is used to conduct numerical simulation analysis of landslide accumulation body.The calculation shows that: in natural state,the numerical calculation shows that the plastic zone does not form a continuous through zone in the slope body.The dynamic response of landslide accumulation body at different positions under earthquake is different obviously.On the surface and inside of the slope,the displacement gradually increases with the increase of the elevation,and the maximum displacement is located on the slope surface.The velocity response shows elevation amplification effect on the inner and surface of the slope,and the maximum velocity appears on the surface of the slope.After loading the seismic condition,the through shear strain increment appears at the sliding surface of the accumulation body,which proves that the landslide is more prone to slip under the seismic action compared with the natural condition. |
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