Study On Deformation Characteristics And Stability Of Soil-Rock Mixed Filling Subgrade Under Traffic Load

The phenomenon of uneven settlement and stability decline of soil-rock mixed subgrade caused by long-term traffic load is frequently encountered in the construction of expressways in western China.In this thesis,the soil-rock concrete subgrade model test was conducted by using the electro-hydraulic servo test system as the traffic load simulation device,the influence of the frequency and amplitude of traffic loads on the settlement of the earth-rock concrete subgrade was analyzed.Through FLAC3 D finite difference software,the impact of factors such as stone content,slope,filling height and vehicle speed were further considered.The results of the study are summarized as follows:(1)Through the model test,the relationship between the settlement characteristics of soilrock mixed filling subgrade and the load frequency and load amplitude is analyzed.The study shows that the subgrade settlement develops rapidly in the early stage of loading,and gradually tends to be stable in the later stage of loading.The closer the load frequency is to the natural frequency of the subgrade,the greater the settlement of the subgrade.The rate effect of dynamic load can strengthen the subgrade,and the larger the load frequency is,the more obvious the rate effect is,and the better the reinforcement effect is;the subgrade settlement decreases with the increase of load frequency,but the decreasing range decreases;with the increase of load amplitude,the subgrade settlement increases continuously,and the increasing range increases continuously.(2)The effects of stone content,slope,filling height and vehicle speed on the settlement characteristics of soil-rock mixed subgrade under traffic load are studied by using FLAC3 D software.The study shows that under the action of traffic load,the settlement development of subgrade at different buried depths lags in different degrees,and the deeper the buried depth is,the stronger the lag of settlement development is;the stone content has a significant effect on the subgrade settlement,and with the increase of stone content,the settlement value at the top of the subgrade decreases greatly,but the stone content has little effect on the settlement at the deeper buried depth,and the slope of the slope only has a weak effect on the displacement near the slope.The height of fill has a great influence on the settlement of subgrade under traffic load.According to the working condition of rigid foundation in this thesis,the higher the filling height is,the greater the settlement of subgrade is.In the early stage of load,the increase of filling height makes the settlement of subgrade tend to become larger,while the decrease of filling height will make the subgrade rebound deformation and reduce the settlement value.The increase of vehicle speed can strengthen the rate effect of dynamic load and strengthen the subgrade structure,but at the same time it will increase the load amplitude and increase the settlement and deformation of the subgrade.(3)Through FLAC3 D,the decline trend of potential sliding surface under different design conditions is obtained by quasi-static strength reduction method,and the dynamic safety factor of slope is solved by vector sum method using Fishlanguage.The study shows that under the same working conditions,the slope safety factor calculated by the vector sum method is less than that calculated by the strength reduction method,and the stone content,slope slope,filling height and vehicle speed all have significant effects on the dynamic stability of the subgrade.The influence is as follows: slope slope > filling height > stone content > vehicle speed.