Safety Risk Assessment Of Expansive Soil Cutting Slope Based On Fuzzy Ideal Point Method

The construction of highways in expansive soil areas will inevitably encounter cut slopes.The safety risk assessment of the slopes has become the focus of attention in the field of road engineering.Because expansive soil has special properties such as crack development,swelling and shrinking deformation,strength attenuation,moisture absorption and disintegration and over-consolidation,at the same time,there are uncertainties in the natural environment,geological conditions and engineering activities in the construction and post-construction phases.It is determined that the safety risk assessment of the expansive soil cutting slope is an unpredictable and multi-factor coupling process.In order to ensure the safety and stability of the expansive soil cut slope during the construction and operation phase,scientifically evaluate the slope stability and risk level,this article comprehensively adopts the methods of literature review,field investigation,theoretical analysis and engineering examples to thoroughly study the instability mechanism and influencing factors of the expansive soil cut slope.Based on the expansive soil cut slope of Guangxi Nanning-Youyiguan Expressway,the ideal point method is used to calculate the index weight,combined with the fuzzy theory to calculate the relative membership degree vector of each index,and the safety risk assessment of the expansive soil cut slope based on the fuzzy ideal point method is carried out.The main research contents and results of this paper are as follows:(1)By analyzing and controlling the instability factors,action mechanism,damage scale and landslide form of the expansive soil cut slope,systematically summarized the instability characteristics of the expansive soil cut slope,and analyzed the influence of the slope during the construction period and the post-construction period.Stability risk factors,the influencing factors of slope stability are discussed,which lays the foundation for constructing a risk assessment index system for cutting slopes in expansive soil areas.(2)Based on the basic theory of risk assessment,the principles of selection of the evaluation index system and the existing problems of selection are given,and four types of 17-item edges are established with slope morphology characteristics,hydrology and natural environment,soil evaluation indexes and engineering construction status as the criterion level Slope risk assessment index system.(3)The ideal point method based on the comprehensive weighting of the analytic hierarchy process and the entropy weight method is used to calculate the slope evaluation index weight,and the fuzzy comprehensive evaluation is used to calculate the relative membership degree vector of each index,and the expansive soil cut slope risk evaluation standard is formulated.A safety risk assessment model for cutting slopes of expansive soil based on fuzzy ideal point method is established.(4)For the 4 expansive soil cutting slopes of the K130-K144 section of Nanyou Road,the built model was used to conduct dynamic risk assessment of the slopes to be evaluated without supporting measures and flexible supporting measures,and the evaluation results were found It is consistent with the actual working conditions,and compared with the results of evaluating the slope grade using the current guide method to verify the rationality and feasibility of the evaluation results obtained by the fuzzy ideal point method.