Study On The Settlement And Controlling Criteria Of Existing Highway During High-speed Rail Tunnel Construction Underpassing By Conventional Method

With the development of China's infrastructure construction and tunnel engineering projects.More and more cases of underpassing projects have emerged.The construction of the underpass project is difficult and the impact of such projects on the existing routes is high,so it has been widely concerned by domestic and foreign experts.This paper takes a high-speed railway tunnel in Chongqing as the research background.The tunnel penetrates the existing main highway and ramp.The length of the lower section is492 m and the maximum depth of the tunnel is 65 m.The rock layer of the tunnel is mainly composed of strong weathered mudstone sandstone.Based on Peck's empirical formula,field data and numerical simulation.This paper studies the existing highways and discusses the influence of different construction methods of high-speed railway tunnels on ramps and main roads.Then analyzes the sensitivity of the factors affecting the width coefficient of the settlement tank.The main research contents are as follows:(1)Based on the Peck empirical formula and use the Midas to simulate the excavation,and study the influence of the double-side drift method on the main road and the ramp of the expressway.The reliability of numerical simulation and the settlement law of pavement caused by tunnel construction are verified by monitoring data.The results show that although the settlement law of pavement accords with the Peck empirical formula,the settlement groove width coefficient and the maximum settlement value of the road surface and the empirical formula are still quite different.(2)Using Midas to study the effects of tunnel construction method,footage of excavation and support measures on road stability,the results show that in controlling road surface settlement and tunnel surrounding rock deformation,double-side drift method,1m footage of excavation and the combination of advanced support and initial support are superior to other methods.(3)Based on the empirical formula of Peck,in order to obtain the factors that have great influence on the width coefficient of the settlement trough,and the relationship between the width coefficient of the settlement trough and its relationship,this paper uses Midas to analyze the Poisson's ratio and viscosity of different soils.Convergence,internal friction angle,different tunnel depths and the influence of different tunnel radius on the highway,and then use originallab to fit the calculated data.The results show thatthe tunnel depth and tunnel span have a great influence on the settlement tank width coefficient and the settlement tank width coefficient is linear.(4)By studying on the damage form of uneven road settlement,The linear relationship between the width coefficient of settlement trough and the buried depth and the tunnel radius is obtained by using the formula fitted in chapter 4 of this paper.Based on the relevant specifications,the control criteria for the maximum settlement value of the permitted roads under different tunnel radii and different tunnel burial depths were obtained.