The Spatial Distribution And Stability Evaluation Of Landslides In Loess Hilly Region

Loess landslides are widely distributed in the loess hilly region where the geological environment is poor with dense gullies and river networks.Zhidan county is located in the loess hilly region,Where the loess landslide is the most distributed type of geological disaster in this region.On the basis of field investigation,data collation and experiments,this paper studied the distribution regularities of landslide by using GIS spatial analysis technology.The basic physical and mechanical properties of loess are analyzed through the physical and mechanical test of landslide soil.Finally,the stability of shallow loess landslides under different rainfall was evaluated by using SINMAP model,and Geo-studio software was used to evaluate the stability of two types of loess landslide under different conditions.The main conclusions are as follows:(1)The spatial distribution of landslide in Zhidan county was summarized.The distribution of loess landslides is characterized by spatial aggregation.The areas with high landslide density are concentrated in the Zhou River basin.The area and volume of landslides are large in the middle and west of Zhidan county,and the spatial distribution of landslides have obvious fractal characteristics.Landslides are mainly developed on the quaternary loess strata with the elevation between 1300 ~ 1550 m,the slope between 20 ~ 40 °,relief degree between20 ~ 60 m.Landslides occur frequently from June to September every year.In addition,the distribution of landslide can be affected by the rivers,roads and land use.(2)According to the experiments of soil samples collected from Zhifang landslide and Menggoumen landslide,the basic physical and mechanical properties were analyzed.The cohesion of natural soil samples was between 9.23 kpa and 19.93 kpa,and the internal friction Angle was between 32.19° and 34.31°.The cohesive force of saturated soil samples ranged from 2.1kpa to 10.5kpa,and the internal friction Angle ranged from 33.9° to 35.56°.The increase of loess moisture content significantly reduced the shear strength.(3)The SINMAP model was used to evaluate the stability of shallow loess landslides inthe Zhouhe River Basin.The overall stability of the basin is high,and the unstable area enlarges with precipitation increasing but does not exceed half of the entire study area.As the rainfall increases,the surface area of different stability level changes,and the stability level of the landslide changes accordingly.The extremely unstable region is always located in a place with large slope and strong erosion of water flow,and the variation range of extremely unstable area is small.(4)The Slope/W module of Geo-studio was used to establish the stability evaluation model of landslide.The evaluation results show that the Menggoumen landslide was stable under natural and saturated conditions.Zhifang landslide was unstable before treatment and in a stable state after the slope cutting treatment.