Risk Analysis And Engineering Application Of Highway Slope Stability Considering Rainfall Condition

Highway slope instability will not only lead to casualties,property damage,but also have impact on national economic construction and social stability.The influence of rainfall on slope of the highway is wide and the damage is significant.However,due to the complexity of the infiltration process,most of the practical projects only consider the effect of rainfall by static groundwater level or strength parameter reduction.This approach ignores the interaction between the stress field and the seepage field,which will inevitably affect the accuracy of the calculation results.In addition,in the aspect of slope stability risk research,most of the evaluation methods have strong subjectivity,and lack of risk research for rainfall infiltration slope in rainwater concentration area.In order to analyze the stability and risk of slope under rainfall infiltration,Geo-Studio software was used to establish the coupling model of seepage field and stress field.The influence of various factors on slope stability under rainfall condition was analyzed as the basis for slope risk assessment.The main research contents are as follows:(1)The research status of unsaturated soil slope was expounded,the theory of unsaturated soil seepage and unsaturated soil strength,the analysis method of seepage and stability of highway slope under rainfall conditions,the coupling equation of seepage-stress and the conditions of solution were also introduced.(2)Four types of fluid-solid coupling models according to homogeneous slope,fill slope,binary structure slope and weak sandwich slope were established.And the seepage field,stress field and stability safety factor of slope were calculated respectively.The effects of geometric characteristics,geological structure and hydrological conditions on the stability of four types slopes under rainfall conditions were compared.According to the decrease of the safety factor,the influencing factors were sorted according to the degree of importance.It was found that the different types of slope sorting results were different,but the rainfall was the most important factor to the slope stability.(3)The risk assessment system for filling slope,binary structure slope and weak sandwich slope under rainfall infiltration was establish.By using the method of index system,the weight of each risk index was determined according to its importance,and the method of determining the risk index value according to the decrease ratio of safety factor was put forward,which may reduce the influence of subjective factors in risk assessment to a certain extent.(4)Aiming at actual landslide geological disaster control project,two kinds of rainfall schemes were used to establish the calculation model.And it was found that under certain amount of rain,condition of long duration but low intensity rainfall was more harmful to the slope than shorter but heavy intensity rainfall condition.According to the risk analysis results,the risk level of the slope belongs to highly risk,which is consistent with actual situation.On this basis,the anti-slide pile reinforcement model was established,and the influence of the design parameters of the anti-slide pile on the reinforcement effect was analyzed.At the end,a safe,reliable and economical treatment scheme was put forward.The stability calculation and risk analysis method above for rainfall infiltration slope are simple and feasible,which can provide reference for the stability and risk evaluation of similar highway slope in rainfall concentration area.