| Along with the social development in northern Shaanxi in recent years,as well as a large number of human engineering activities in the loess region,sandy loess and silt loess are typical of loess slope disasters.In addition,the ecological environment of the loess region is fragile and geological Disasters occur frequently,so it is urgent to research and analyze the special soil of loess.Due to the wide distribution of loess in my country and the difference in sedimentary environment,there are obvious differences in the stratum structure,material composition and mechanical properties of loess in different regions of China.Many scholars have carried out research on the distribution,origin,material composition,strength and deformation of loess,and a large number of research results have been widely applied to engineering practice and disaster prevention and mitigation in the loess area.For loess slope excavation and treatment,most of them are based on regional treatment experience,and there is little research on the systematic optimization design evaluation system.Therefore,this paper conducts field surveys and relevant data collection on multiple slopes of different soil types in northern Shaanxi.On the basis of this,taking Shagou Chasha loess slopes in Fugu County,Yulin City and Hecaogou silt loess slopes in Zichang City as examples,through the anti-erosion optimization design of different soil slopes,the optimal single slope slope design,A series of studies on the optimal single slope height design and the optimal wide platform design,and finally combined with the TOPSIS analysis method to comprehensively analyze the typical loess slopes,and finally establish an effective evaluation system for the future slope treatment work in this area Provide guidance.The main research results obtained in this paper are as follows:(1)Through comprehensive analysis of the parameter values of silt loess and sand loess under different test conditions,the parameter values obtained under the stress path test conditions are larger than the conservative empirical values and smaller than the conventional triaxial test values.The parameter values in the natural state obtained under the stress path test are in line with the actual situation,and are more instructive for later engineering practice.Therefore,the parameter values under the stress path test conditions can be preferentially used in the later engineering treatment projects.(2)The anti-erosion angle range of typical silt loess slopes in the study area is between 40°and 58°,and the overall slope of sand loess slopes is between 30° and 42°.From the PFC2 D numerical simulation results of silt loess slope and sand loess slope,it can be seen that when the slope ratio of a single slope varies between 1:0.75 and 1:1.05,the magnitude of the displacement change is small.Therefore,it can be intuitively obtained that under the action of water current consistent with the local rainfall erosion,the optimal slope rate of the slope against erosion is greater than or equal to 1:0.75.(3)In this paper,after orthogonal design experiments on the factors affecting slope stability(slope height,slope ratio,wide platform position,wide platform size,and number of wide platforms),it is determined that various factors contribute to the stability of the slope during the excavation process.The degree of sexual influence.And on this basis,by controlling other factors and variables,numerical simulation research is carried out on the influence of each factor on the slope stability,and the optimal value under the action of each single factor is obtained by statistics.(4)Analyze and summarize the optimal values of slope elements obtained in the numerical simulation process with the characteristics of the study area,combine the economic indicators,technical indicators and environmental indicators that affect the slope treatment project,and use AHP-EW-TOPSIS to establish Comprehensive evaluation system for the optimal plan of slope treatment. |
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