Early Identification And Stability Analysis Of Accumulated Landslides In Lushui Section Of Nujiang River Basin

Nujiang prefecture belongs to the "three districts and three prefectures" special poverty area,and it is also an important section of the joint construction of the "Belt and Road".The local area had to be developed and utilized on the gentle slope platform of the ancient accumulation body.With the human engineering activities and the local rainy climatic conditions,many ancient landslide accumulation bodies were revived and disasters occurred frequently,which seriously affected the use and construction of infrastructure and the safety of people's lives and property..This paper focuses on the needs of disaster prevention and mitigation in the study area,takes the Lushui section of the Nujiang River Basin as the research object,and relies on the disaster geological survey project of the Lushui-Mangshi section of the Nujiang River Basin.Analyze the types and causes of accumulations in the area,use InSAR technology to identify hidden trouble spots in the study area,and conduct field investigation and verification.The landslide evolution and the mechanism of formation at two typical points are analyzed,and the stability of the landslide under heavy rainfall conditions is analyzed.Mainly obtain the following knowledge:(1)Accumulation bodies in the Lushui section of the Nujiang River Basin can be divided into:landslide accumulation body,collapse accumulation body,residual slope accumulation body,alluvial accumulation body;spatial distribution can be divided into:river valley area(including river bed and river valley slope area)and activities Fracture zone accumulation.Each type of accumulation body has its own accumulation characteristics in terms of plane shape,terrain conditions,material structure,and slope structure.(2)Through investigation and statistics,the geological conditions of disaster-preserving landslides in accumulated layers in Lushui City were basically ascertained.Landslides are affected by topography and landforms,and generally occur within a range of slopes of 15°to 35°;landslides with a slope height of 0 to 50m are most developed,accounting for about 50%of the total number of landslides;harder gneiss and granulite The landslides are relatively developed within the range of the hard basalt and clastic rock group,accounting for 41.5%of the total;the landslide development has a good correspondence with soil erosion,and they are mostly distributed in the water and soil loss areas along the Nu River;the accumulation layer landslides The closer to the fault,the number of landslides increases.58.6%of the landslides are developed within 600m from the fault;affected by human engineering activities,the proportion of landslides within 100m from the highway can reach 56%.(3)Carry out comprehensive remote sensing recognition of accumulated landslides based on InSAR and high-resolution images,combined with field investigation,a total of 31 landslide hazard points were identified,mainly distributed on both sides of the Nujiang River and near the Nujiang fault zone,of which,not in the geological disaster database 8 newly identified hidden danger points of landslides provide strong technical support for local disaster prevention and mitigation.(4)Focused on the analysis of the formation process and formation mechanism of Zhuangfang landslide and Oumula landslide.Based on Midas software,numerical analysis of stress and deformation of landslide under different working conditions was carried out.The simulation results are consistent with the on-site investigation of deformation signs.