| The Baoshan region of Yunnan Province has a subtropical plateau climate in the southwest monsoon region,with a wide distribution of red clay and frequent rainfall.After handling and deposition,the red clay was damaged,and the cementation connection between the primary red clay particles no longer exists,resulting in significant differences in the physical and mechanical properties of the secondary red clay and the primary red clay.With the development of urban high-speed construction,the problem of secondary red clay slope engineering has become more and more prominent.Under the action of rainfall,the secondary red clay slope will lead to peeling,erosion and landslide due to the water absorption and expansion of the soil.Its unique properties promote the formation of landslides,resulting in repeated landslide disasters.The secondary red clay slope stability evaluation method of Baoshan Tianli School was compared and analyzed,including numerical analysis method,strength reduction method and limit equilibrium analysis method.Finally,the strength reduction method in the Midas GTS finite element software is selected to analyze the stability of the slope in the case of rainfall infiltration.Through field field investigation,exploration and indoor geotechnical testing,the geological background and landslide formation mechanism of the research area were deeply discussed.Secondly,through the finite element numerical simulation software,the influence of the secondary red clay layer on the overall stability of the slope at different natural moisture content is analyzed.Finally,on the basis of the above analysis and evaluation,the rainfall infiltration stability of the slope is analyzed and the corresponding treatment measures and suggestions are provided according to the actual situation.This paper focuses on the stability change trend of the secondary red clay slope from natural unsaturated state to saturated state and the correlation between the secondary red clay layer and the slope change.The main conclusions are as follows:(1)Through field research on the instability characteristics of the secondary red clay slope of Tianli School,it was found that rainfall,landslide height,slope,soil properties,etc.all have different effects on landslide instability to varying degrees.Finally,it was determined that the secondary red clay landslide instability form of Tianli School was mainly peeled and destroyed on the surface under natural Peeling,this kind of damage does not involve the structural problems of secondary red clay landslides.The shallow part of the landslide is mainly affected by erosion and collapse under the impact of rainfall,soil cracks,weak layers and stress concentration.(2)Five secondary red clay samples with different natural moisture content in the landslide area were selected for consolidation tests to explore the impact of water content on their compression characteristics.The results show that the compression characteristics of secondary red clay have a highly nonlinear change trend with the increase of consolidation pressure,and the moisture content has a significant impact on the compression characteristics of the soil.In addition,the shear test analysis of 5groups in the landslide area of Tianli School and 155 groups of secondary red clay with different water content in the area around the landslide was found to have a great impact on the results of adhesion and internal(3)In order to study the influence of secondary red clay on the landslide displacement field,stress field and safety coefficient of Tianli School under different natural water content conditions,based on Midas finite element software and limit balance method,it is found that the landsli School landsli arc damage surface is mainly distributed in the plain filling and secondary red viscosity from the front side of the slope to the In the soil layer,the shear stress is mainly concentrated at the foot of the slope,and the landslide plastic damage area and shear stress range increase significantly with the increase of water content.The safety factor and the adhesion of secondary red clay show a linear growth trend,and there is no obvious relationship with the internal friction angle φ.(4)In order to study the impact of rainfall infiltration on the overall stability of the secondary red clay layer and landslide of Tianli School,combined with the theory of rainfall infiltration,the law of the depth change of secondary red clay rainfall infiltration in Tianli School is analyzed under six different rainfall conditions.Based on Midas GTS finite element software,the change law of landslide under different working conditions is analyzed from the perspective of pore water pressure,stress field,displacement field and safety coefficient.Finally,countermeasures and suggestions are given for landslides in stable,peristaltic and sliding stages under different working conditions. |
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