Study On Back Analysis Of Soil Parameters And Dynamic Design Method Of Highway Slope

With the rapid development of national economy,highway construction extended to mountainous areas in recent years,which induced the increasing issues of slope stability.The instability failure of the slope is mostly related to the unreasonable design of reinforcement.The accuracy of the shear strength parameters of rock and soil is an important factor restricting the stability analysis of the slope and the rational design of the reinforcement.In the actual project,the sliding zone of the slope always lays deeply.It is difficult to accurately seek the actual location and it is easily causing large disturbance when sampling.Therefore,it is difficult to obtain accurate strength parameters through experiments.Above all,how to quickly and accurately determine the shear strength parameters of rock and soil,and rational design of slope reinforcement combined with the characteristics of slope is an urgent problem in the practice of slope engineering.Based on the engineering example of cutting high slope of Renhua-Boluo expressway in Guangdong Province,this paper studies the method of back analysis of shear strength parameters and dynamic design of highway slope.Combing with the geological conditions and strengthening means of the slope,establish the deformation monitoring system of highway slope,and according to the the monitoring data and the survey data judge the position of the potential slip surface of the slope;Research on the sensitivity relationship between rock shear strength and slope safety factor,combined with finite element strength reduction method and displacement back analysis method respectively propose shear strength parameter inversion methods for simple slopes and complex slopes,and apply it to the K443 cutting slope project of Renhua-Boluo expressway;Combined with the results of monitoring and numerical analysis analyse the multi period instability mechanism of the slope,and according to the results of the slope stability analysis under the conditions of rainfall optimize the reinforcement scheme of the slope.(1)Slope deformation monitoring provides a rich basis for timely understanding of slope deformation dynamics and system study of slope instability mechanism.For slope reinforcement with anchor cable(anchor),the site monitoring content should include surface displacement,deep horizontal displacement and anchor cable tension.The deep displacement data in the monitoring process are very sensitive to the stability of the slope,and the key information of the potential sliding surface can be accurately judged by the joint surface displacement monitoring and the monitoring of the structure stress.(2)Friction angle is more sensitive than cohesive force to safety factor,in the parameter inversion calculation,the friction angle can be retrieved by assuming cohesive force to obtain more accurate results.The two inversion methods of shear strength parameters can meet the requirements of accuracy in calculation and can be well applied to their respective engineering fields.(3)The silty sandstone example shows that the safety factor of the slope decreases significantly under the condition of full rainfall,and the influence of rainfall factors should be fully considered in the design of slope reinforcement scheme.Slope construction process should be timely reinforcement and protection,and gradual excavation and progressive support.When there is danger of collapse and slip in the process of slope excavation,the excavation should be stopped immediately,and backpressure the toe of slope with soil,and the waterproof cloth should be covered on the slope to prevent rainwater from further infiltration into the slope.