Experiment And Characteristic Analysis Of Gravity Erosion Process On Red Soil Slope In Xiangtan Are

China is one of the countries with the most serious geological disasters in the world.Geological disasters threaten social and economic development and the safety of people’s lives and properties.Xiangtan is located in the east-central part of Hunan Province,and is an area prone to geological disasters in my country.Based on field investigation and data statistics,this paper designs an indoor test model and test plan.Taking laterite as the object,the experiment and characteristics of the slope gravity erosion process are carried out.Based on field investigation,indoor simulation test,data and theory,and numerical simulation analysis,the real-time dynamic observation of the macro erosion evolution process under heavy rainstorm was realized,the variation characteristics of the meso parameters inside the slope were analyzed,and Xiangtan was revealed.The process characteristics and mechanism of gravity erosion on laterite slopes in the region.The results show that:(1)From the perspective of development and damage of channel erosion,rill erosion?cut gully erosion?gully undercut?gravity erosion is the main development and damage form of slope erosion,and trace erosion is from the perspective of slope erosion development.And the trace erosion will continue to exist in the process of slope erosion and damage after the start of the source erosion.(2)When the slope and gully run through the slope surface,the increase of soil moisture content leads to the increase of self-weight,the softening of soil,the decrease of shear strength,and the sliding force is greater than the anti-sliding force,resulting in instability failure;When the slope is damaged,the moisture content increases to a certain extent,but it does not reach the saturated moisture content.The continuous rainfall causes the integrity and stability of the slope to be disturbed,and eventually instability failure occurs;at the same time,the increase of moisture content promotes the slope.The small block collapse and flow slip on the empty face at the front of the body further aggravate the traceability erosion phenomenon of the slope.(3)The pore water pressure always changes with the change of soil moist ure content during the initiation of slope gravity erosion,and the pore pressur e usually undergoes a stepwise change process of increasing-decreasing-re-incre asing-re-decrease.Infiltration of water until gravity erosion starts is the main s tage of pore water pressure increase,after which the pore water pressure will dissipate or decrease sharply.(4)During the experiment,the amount of sediment carried by rainfall confluence basically depends on the amount of collapse in the ditch.Small-scale block flow slips,slumps,and collapse materials usually collapse into channels or directly into accumulation areas,migrate to accumulation areas or gradually spread in accumulation areas with confluence and rainfall erosion and re-erosion;large-scale slope gravity The source of erosion collapse directly falls into the accumulation area,and with the increase of the amount of collapse,it tends to gradually increase to the notch.The reerosion effect of rainfall and the confluence of the slope surface of the accumulation makes the fine particles of the accumulation gradually increase to the accumulation area.The leading edge gathers and the thickness increases gradually.Under the action of scour and silting,the accumulation gradually diffuses to form a larger alluvial cone.(5)By collecting the total amount of runoff samples flowing through the accumulation area in the whole process and measuring the total amount of material in the accumulation area,the total amount of dry sediment produced by the runoff and sand production in the first and second experiments was 49.47 kg,respectively.59.79kg;during the test,the dry soil mass of the accumulation area was 344.42 kg and335.92 kg respectively,that is,the total amount of sediment produced in the whole process of the slope gravity erosion test was 393.89 kg and 395.71 kg,respectively.According to the results of the indoor model test,the total amount of erosion and sediment production in the two groups of tests during the whole process is similar,and the test results are reliable.Combined with the similar conditions of the experiment and the study area,the sediment yield from gravity erosion of the slope in the study area can be estimated,which can provide a scientific basis for disaster prevention and mitigation projects in the study area.(6)The trend of numerical simulation and experimental observation is similar,but there is a certain deviation in the change of measured value.On the other hand,the simulation process is mostly ideal conditions,affected by boundary effects and considered less interference factors,and there is still a certain gap with the actual change process.(7)In the management of gravity erosion disasters,prevention and control measures should be carried out according to the factors and local conditions according to the main factors of different developmental stages of the slope gravity erosion.Predisaster prevention,blocking the development chain of gravity erosion and the action between various influencing factors,and reducing the intensity of action;post-disaster protection and dredging,to minimize disaster losses.