| With the rapid increase in the number of people traveling in China,the operational burden of existing railway facilities is also increasing.The addition of double lines in the vicinity of existing railways has been increasingly applied in engineering.As a control engineering railway tunnel,it is usually the case that the parallel tunnels reserved by the existing lines are expanded into double-track tunnels.In this paper,the Xinshan Shutuo Tunnel of Yuhuai Double Line is used as the engineering background.The numerical simulation of the finite element software is combined with the monitoring data of the tunnel construction site to study the lining of the existing Shanshutuo tunnel during the expansion of the Xinshanshutuo tunnel.The dynamic response law along the longitudinal and lateral directions is analyzed,and the dynamic response law of the lining under different dike angles and different excavation footage is analyzed.The main research contents and results of this paper are as follows:(1)Based on the data of on-site monitoring of excavation blasting,the linear regression method is used to derive the formula of the blasting vibration velocity of the explosive powder,vibration velocity and distance between the new Shanshutuo tunnel,which provides engineering reference for subsequent blasting construction.And reference;(2)A three-dimensional numerical model is established for the new and old Shanshutuo tunnels.Through the numerical simulation analysis,the longitudinal attenuation law and the lateral attenuation law of the vibration velocity near the existing tunnel lining are obtained,and the parallel guiding pits are obtained accordingly.During the blasting excavation process,the monitoring and protection position is strengthened near the blasting side of the tunnel lining;(3)Based on the geological conditions of the project,the three-dimensional numerical model of the surrounding rock environment is established,and the increase and decrease of the vibration velocity and displacement at each point of the existing tunnel lining are obtained.It is in good agreement with the theory of blasting stress wave,which verifies the reliability of numerical analysis;(4)Using the numerical simulation results to calculate the safety factor of the existing tunnel lining,and obtain the safety reserve of the existing Shanshutun tunnel under different working conditions,so as to comprehensively grasp the safety of the tunnel during the excavation blasting construction. |
