The Research Of Relationship Between "9.16" Mass Of Shallow Landslide In Changning,Yunnan And Vegetation Type

This paper focuses on the research of the relationship between the"9·16" mass shallow landslide in Changning County,Yunnan Province and the vegetation types.The purpose of this study was to further understand the effects of different vegetation types(herbs,shrubs,and Qiao Ben)on the development of landslide and on the slope instability in Mountain Watershed environment.Mainly based on the field investigation of landslide and the measurement of the characteristic parameters of the sliding body,the characteristics of the sliding body under the high vegetation coverage rate were analyzed,the root system content and soil physical indexes of different vegetation types were calculated,the detailed content of the calculation is the root mass density,the natural density of soil,the soil natural water content,the soil saturated water content,the soil specific gravity,the soil porosity,the soil organic matter content and the soil bulk density.The paper analyzed the reasons of the change of the index of different vegetation types with the depth of soil layer and its relationship with the depth of the root system.Linear regression and partial correlation analysis were used to study the relationship between the indexes and the characteristics of the sliding body erosion.The results showed that the root depth of herbaceous vegetation which can be influenced in the area was 0?30cm,and the depth of root system of shrub vegetation which can be influenced was from 0 to 50cm,and the root depth of the vegetation which can be influenced was from 0 to 70cm.The research results have certain guiding significance for slope treatment and soil and water conservation.The main conclusions of this paper are as follows:(1)Under the same conditions,the characteristics of the sliding body show obvious difference on the slopes of different vegetation types.(2)The root system of the plant will affect the physical parameters of the soil in the root zone,and there are significant differences between the different types of vegetation in the same soil depth.(3)The root system of plants,soil organic matter and soil porosity can promote the erosion intensity of the sliding body,while the natural density of soil and soil bulk density have an inhibitory effect on the sliding body erosion intensity.In the vegetation slope soil,the maximum value of soil physical index difference between adjacent layers corresponds to the fastest rate of soil root content reduction,and in the depth range,landslide erosion depth or erosion intensity and depth of root elongation are closely linked.(4)The diversion effect of vegetation root group is better than single vegetation roots under rainfall.The results show that the rainfall accumulation in shallow soil and the change of soil mass index lead to the instability of slope with vegetation development.(5)Long time days rainfall before the landslide and high intensity rainfall on the eve of the landslide is the main predisposing factors,however,the high density development of shrub vegetation and tree vegetation in the region promoted the occurrence of landslide.