Research On The Key Construction Technology Of The New Tunnel Under-crossingexisting Railway Roadbed And The Stability Of The Railway Roadbed

During excavation,due to excavation disturbance,ground loss and consolidation settlement,the settlement of rock and soil above the construction tunnel will lead to the movement or deformation of the railway subgrade above the tunnel.How to take reasonable measures for tunnel excavation and quality control and how to minimize the influence of tunnel excavation on the stability of existing railway subgrade is a problem that can not be ignored.On the basis of Chongqing-Changshou high-speed Tang Jiazui tunnel engineering which under the railway line and passenger railway,due to the railway line and passenger railway is not the same as the control standards for subgrade settlement and settlement difference.Therefore,this paper through different excavation methods and different excavation,combining with construction factors,the key construction techniques of the subgrade section of the lower railway are studied,and get the following conclusion:(1)When the excavation approach is 1m,the subgrade settlement and differential settlement caused by the method of double side and step method are within the range of control value,and the subgrade settlement and differential settlement caused by the construction process of the three step method do not meet the control requirements.(2)From the analysis of construction safety and control standards,double side drift method is more suitable and conservative.From the analysis of the construction process conversion and construction period,the step method is more suitable,but in the process of construction,the closed loop of the step support should be carried out in time and the emergency treatment measures should be done.(3)Tunnel excavation on the railway line and passenger railway along the railway to the affected area in the range of 50 m line plane intersection.(4)The reliability of numerical simulation is verified by monitoring data.The field construction can be comprehensively analyzed through numerical simulation and field monitoring data,and the construction sequence and supporting parameters can be determined.