The Disturbance Effect And Parameter’Optimization Of Shield Construction Through The Orbital Group Over Long Distances

In recent years, with the rapid development of urban rail transit in our country, the earth pressure balance shield construction technology has been widely applied. It is completely significant to have a research on the topics of evaluating the impact of the building (structure) nearby, especially the impact of the train tracks. In this paper, combined with the scientific and technological project of China Railway Tunnel Group and based on the engineering background of Zhengzhou Metro Line one acrossing the Zhengzhou Railway Station, the research of static and dynamic response in the process of shield crossing track group is carried out, and the optimized method of construction parameters is put forward by comparing with and analyzing the monitoring data. The main research is as follows:(1)The formation mechanism and simulation method of train dynamic load is analyzed, and the discipline of dynamic calculation in underground engineering is discussed on the perspective of dynamics.(2) The FLAC3D calculation software is applied to analyze the shield mechanical behavior on the condition of having the train dynamic load or not. On the condition of dynamic train loads, the formation stress and stratum displacement is analyzed in every step of construction process;Otherwise, the time-history of formation stress,vault displacement, closed segment dome displacement and axis surface settlement is analyzed at the speed of20km/h,40km/h and80km/h in every step of the construction process.(3) Along with the left and right line successive excavation of double parallel tunnel, the surface settlement discipline of shield cross-section and shield axis settlement point in the process of shield excavation is obtained by analyzing the monitoring data which determined the best time to control surface settlement.(4) The formation disturbance discipline along with grubbing shaving torque is obtained by comparing with and analyzing the numerical simulation and monitoring data. And the optimized method of construction parameters and experience estimation formula of the earth pressure, the thrust force and torque of cutting wheel is put forward.