Analysis And Control Of Settlement For Metro Shield Tunnel Tuneling In Weak Stratumay Underneath Existing Railway

In the process of metro construction,shield tunneling machine encounter through the negative phenomenon inevitably,because of the limitation of geological environment and lines.In this paper,taking Tianjin metro line 5 as the engineering background,studies settlement law and control technology for metro shield tunnel tuneling underneath existing railway.Through numerical simulation with FLAC3 D,this paper studies the settlement law of the railway subgrade under different construction intervals and different tunneling parameters,also studies the settlement law of the railway subgrade under single and double line tunnel excavation.Through the information construction and the multi-level grouting control technology to realize the control of settlement.The main work content and conclusions are as follows:(1)According to the actual project,the corresponding shield tunneling model is constructed.(2)The effects of different construction intervals and different tunneling parameters on the settlement of railway subgrade are analyzed.The settlement and settlement rate are easier to control as the distance of construction intervals become more and more remote.The increase of face pressure and grouting pressure will reduce subgrade settlement.Railway subgrade settlement increases significantly with grouting quantity increased.(3)The paper analyzes the settlement rule of railway subgrade for single-line construction and double-line construction.The transverse settlement groove same as that of Peck theory when single line constructed.It has obvious superposition effect on the subgrade transverse settlement groove when the right line constructed after the left line.(4)The concrete work of information construction is carried out,and the monitoring data are analyzed in detail.The monitoring data shows that the settlement and settlement rate of railway subgrade and track and ground surface around subgrade are all within the control standard.(5)In this paper,the effect of secondary radial grouting constructing is analyzed,and the measured settlement groove is compared with the simulated settlement groove,the validity of the numerical simulation is obtained.