Research On Mechanical Effect Of Main Structure During Tunneling By NTR Method And Operation Period Under The Railway Station

With the development of the national economy,the underground engineering construction technology has also been improved.In recent years,the new pipe curtain method has been widely used as a relatively new construction technology.The new pipe curtain method is also called NTR(New Tubular Roof Method).The construction method is mainly applied to the tube curtain structure formed by cutting and connecting large-diameter steel pipes under the condition of loose soil and water-rich stratum and strict settlement control requirements.Compared with the traditional mining method,the structure is waterproof and bears load.With a more significant improvement,it is effective in controlling surface settlement and reducing the disturbance of construction to adjacent structures.This paper relies on the railway station project of Yingze Street in Taiyuan.The steel pipe is cut and supported.The influence of the deformation and surface settlement of the pipe curtain structure and the bag-passage structure,and the mechanical response of the main structure during the construction and operation period under the dynamic load of the train are carried out.In-depth research and analysis of actual monitoring data,the main research contents are as follows:(1)Under the static load condition,the finite difference software Flac3 D is used to establish the numerical model.The effects of different steel pipe cutting length,different cutting order and different main structure construction timing on the deformation and surface settlement of the pipe curtain structure are carried out.Cutting parameters,cutting sequence and optimization of the timing of the main structure.(2)According to the actual jacking sequence of the steel pipe at the construction site,the numerical analysis is carried out to analyze the stress of the pipe curtain structure during the cutting and supporting of the steel pipe under the NTR method,and the settlement characteristics of the channel and the platform are analyzed.Provide a reference basis.(3)Through the three-dimensional numerical calculation,when the pipe channel is passed through the pipe curtain structure,the structural deformation of the bag channel structure and the settlement of the bank are analyzed in depth,and the structural safety is evaluated.(4)Using three-dimensional numerical dynamics calculation,the dynamic response of the steel pipe cutting,supporting stage and soil excavation inside the main structure under the dynamic load of single row and two trains is studied.The force of the train operation on the curtain structure is analyzed.The law of influence of deformation.(5)Through statistical analysis of the measured data of the channel and platform settlement during the jacking process of the steel pipe,it is shown that the NTR method can effectively control the formation deformation.