Stability Analysis Method Of Expressway Slope Under Static And Dynamic Loads

China is a mountainous country,the mountainous area accounts for about 70% of the total land area.With the rapid development of economy,in order to balance the development between the East region and the west region,the state has implemented the strategy of western development and the "The Belt and Road" strategy in recent years,which has caused a lot of infrastructure to go through mountains and hilly areas.The most obvious is the construction of high speed roads in mountainous areas.When the expressway passes through the mountainous area,there are a lot of slope stability problems caused by excavation and filling because of the route requirements.The stability analysis of the slope encountered in the project is the key technology to ensure the safety and smoothness of the route.Therefore,the research on this subject has important theoretical significance and wide engineering practical value.On the basis of previous studies and relying on the actual mountainous expressway project-Longyong Expressway,this paper systematically studies the stability analysis of expressway slope under static and dynamic loads,taking into account the effects of rainfall scouring and earthquake,and combining with experimental,theoretical and numerical analysis methods.The main research contents are as follows:(1)Through on-site investigation and mechanical test,the physical and mechanical properties,composition and macro-and micro-characteristics of residual rock mass in engineering are studied in detail.The material composition and stress variation characteristics of residual rock mass are explored,and the collapse test of residual rock mass is carried out,which is aimed at the failure of residual rock slope under heavy rainfall conditions.The work has laid the foundation for the slope failure mechanism under heavy rainfull condition.(2)In order to consider the effect of strong rainfall scouring on the stability of weak rock slope,a large scale model test was carried out.The equipment and testing equipment of simulated scouring test are developed,and several groups of tests are designed.The relationship between rainfall intensity,slope length,scouring amount and time is discussed.The whole process of slope instability is analyzed.The sensitivity of influencing factors is analyzed,and the engineering suggestions for slope design are put forward.(3)According to the basic principle of finite element limit analysis,the upper and lower limit theorems are transformed into corresponding mathematical programming models.Based on the platform of MATLAB,the finite element limit analysis program is developed.On this basis,the stability of the soil-borne slope subgrade under static and seismic action is analyzed,the upper and lower limit solutions of the ultimate bearing capacity of the subgrade are calculated,and the calculation results of the ultimate bearing capacity of the subgrade are dealt with dimensionlessly,and the design calculation tables are summarized.The influence of each parameter on the ultimate bearing capacity of the subgrade is discussed in detail.(4)The modified Hooke-Brown criterion is used to describe the nonlinear characteristics of rock mass,and it is directly embedded in the finite limit analysis program.At the same time,a finite element limit analysis program with adaptive mesh is developed.On this basis,the ultimate bearing capacity of rock slope subgrade under static and seismic loads is calculated,and the calculation results are dimensionless,and summarized into a design calculation table for engineering reference.(5)To consider the reliability design of deep-buried rectangular tunnel without considering slope effect,Based on the non-linear failure criterion and the limit analysis theory,a three-dimensional collapse model of the top of deep-buried tunnel is proposed.Supporting force is considered in the virtual work equation of the upper bound theorem,and then different rock parameters are considered as random variables.The sensitivity of the mechanism is analyzed by first-order reliability method and Monte Carlo simulation method,and the influence of the variation of rock parameter coefficients is discussed.Finally,according to the results of the analysis,some suggestions for supporting force design are given for engineering reference.(6)The stability of rock slope with tunnel is analyzed by finite element limit analysis method.According to the actual situation of the project,the finite element limit analysis model of the slope-tunnel is established,and a dimensionless stability coefficient is defined to measure the stability of the slope.The upper and lower bound solutions of the stability coefficients are obtained,and the results are summarized as design calculation charts.Finally,the influence of slope angle and relative position of tunnel on stability coefficient is discussed,and the evolution law of failure mode is also discussed.