| China is a country with many loess distributions,accounting for about 7% of the country's land area.The problem of loess slope stability is always the most important issue in many engineering geological problems concerning loess,and the stability of slopes is the most problematic.Because the slope soil of the loess slope is exposed to the natural environment all year round,under the influence of various external factors such as wind erosion and rainfall erosion,the nature of the slope surface soil is reduced,and slope erosion are formed,Slope collapse and small collapses,slumps,etc.,eventually led to the loss of stability on the slope.The instability of the loess slope's surface will further lead to the destruction of the entire slope.Above all,it is Imperative to study the factors affecting the slope stability and the failure mechanism of the slope surface.On the basis of collecting relevant data,the structure characteristics of the loess slope and the characteristics of the slope instability were fully investigated.The factors influencing the instability of the loess slope were analyzed;indoor experiments were conducted to collect different lateral depth soil samples and the weathering was summarized.The effect of depth deepening on the physical and mechanical properties of slope soil.Based on the laboratory test results,four slope models were established using the MIDAS / GTS finite element software: the original slope(not affected by weathering,rainfall,etc.),the weathered layer was 0.3m,the weathered layer was 0.6m,and the weathered layer was 1.0m.These four models simulated the soil affected by weathering and other factors on the loess slope.With the passage of time,the stability of the slope surface in the case of increased depth of weathering layer,and through the numerical simulation results revealed the shallow surface damage mechanism of the loess slope.The main research results of this paper are as follows:(1)Through regional data collection and site investigation,it was found that the slope damage of loess slopes was mainly due to many external factors such as wind erosion,rainfall erosion,and human activities.Under the joint action of these factors,the structure of the soil on the slope surface is destroyed and the strength is reduced.Therefore,the soil sample was collected from different strata and at different lateral depths on the loess slope and the indoor test was conducted.(2)Through the analysis of the test results,the changes of physical and mechanical properties of soil in different soil layers and different lateral depths of the loess slope are summarized.It can be seen that the physico-mechanical properties of the loess slope soil Is not only related to the soil layer,but also related to the different locations and lateral depths of the soil on the slope surface: with the deepening of the lateral depth,the soil structure is more Compact,relatively fewer pores,and relatively better properties;with the deepening of the vertical depth of the soil,the deep soil is asked to greater self-gravity stress than the upper soil,and the corresponding deep soil structure is more compact,and the pores are relatively more less than.(3)According to the results of numerical simulation,the stability of the slope gradually decreases as the depth of the soil affected by weathering etc.deepens;the depth of the slope is gradually deepened with the weathering of the slope,and the displacement of the slope gradually increases,and the displacements in the middle and lower parts of the slope are the largest;the maximum and minimum principal stresses are concentrated on the contact surface between the soil body and the original slope body on the slope surface due to weathering and erosion;the effective plastic strain belt is concentrated on the slope surface.With the deepening of the soil depth caused by weathering and other erosion on the slope,the angle between the strain belt and the slope gradually decreases,and finally distributes approximately parallel to the slope. |
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