Study On Dynamic Response Of Slope In Changover Portion Ofbridge And Tunnel And Control Of Rock Fall

With the development of the strategy of developing the western region in China,traffic development is particularly fast.This resulted in many bridge and tunnel transition and uphill slopes.Its mechanical behavior is very complex and easy to produce rockfall disaster,but at present,the research on the dynamic response of the bridge and tunnel transition section and the prevention measures of the surrounding rock fall is very limited.Therefore,the research on the dynamic response of the bridge and tunnel transition section and the surrounding slope of the surrounding tunnel caused by the train passing is of great significance.This paper makes use field measurement,numerical simulation and model test to study the dynamic response of the elevation slope of the bridge and tunnel transition section and the measures for protecting the rockfall of the cut-and-cover tunnel.(1)To measure the bridge and tunnel transition section located at the No.58 tunnel at fengsha line.When the train speed is 61.3km/h~69.02km/h,for the same train,the peak acceleration of vibration on the side of the tunnel is nearly 17% larger than that on the side of the bridge.When vehicles with different speeds but the same type of train pass,the faster the speed,the greater the acceleration of vibration between the bridge and the tunnel.(2)In the range of 54.14km/h~95.01km/h,the dynamic response and stress and strain properties of the rear slope are analyzed by numerical simulation.The dynamic displacement(maximum value)and the main stress(minimum value)of the pitching slope of the tunnel caused by the train vibration decrease with the decrease of the train speed;the heavy haul train is carried out.The dynamic displacement(maximum)and the main stress(minimum)of the inverted slope are much larger than that of the tunnel on the pitch slope(maximum value)and the main stress(minimum).The acceleration of the pitch slope increases with the elevation of the pitching slope when the same train loads,and its dynamic displacement is higher with the elevation slope.The increase in degree is reduced.(3)In the range of 54.14km/h~95.01km/h,the dynamic response law of the inverted slope is studied by the indoor model test.The change trend of the acceleration time curve of the inverted slope is related to the type of the train.When the train speed is different,the speed of the train plays a key role in the dynamic response of the slope.When the difference of the train speed is small,the weight of the train plays a key role in the dynamic response of the inverted slope,and the time of the amplitude of the pitching acceleration varies from different trains.When the same load is applied,the acceleration of the rising slope increases with the increase of the height of the slope.The law is basically the same as that obtained by numerical simulation.(4)By summarizing the existing literature on the prevention and control measures of rockfall disasters,the prevention and control measures for rockfall disasters are divided into active protection and passive protection.The protection measures for the falling rocks of the tunnel entrance and exit are mainly protected by the cut-and-cover tunnel.In this paper,the numerical simulation is used to establish the rock proof rock model of the The cut-and-cover tunnel,and the rationality of the overlying soil material on the cut-and-cover tunnel and the reasonable thickness of the overlying soil under the impact of the rockfall load are studied.The dynamic displacement of the falling stone under the same impact load is different,and the greater the dynamic displacement of the soil with higher plasticity,the greater the displacement of the soil.Under the same rockfall load,the maximum velocity and the acceleration amplitude of the model with different soil thickness are different,but the time consuming is different,and the time consuming increases with the increase of thickness.