The Research On The Construction Plan Of The Shield Tunnel Crossing From The Top Of The Mining Tunnel In Small-angle And Close Range

With the constantly improving of the urban rail network, more and more complicated construction situation would inevitably arise on the network nodes' constructions, such as parallel tunnels, overlapped tunnels and crossing tunnels. The construction that a shield tunnel crossing from the top of the mining tunnel with the characteristics of "small-angle, close range and long distance" is extremely difficult in Beijing Metro. To determine a reasonable construction plan, a 3-D finite element analysis is taken into account in this paper. Result show that pouring mining tunnel's lining before the adoption of shield tunnel beneficial to the overlapping tunnels' structural safety during the period of construction.However, the right mining tunnel's lining couldn't complete in the time because of the requirements of the time, so it is very necessary to construct a temporary reinforcement steel support system in the right mining. After an in-depth study on the disadvantaged impact on the mining tunnels, which caused by the second disturbance of the surrounding soil, and the axis' changes of the reinforcement steel support system, the numerical simulated results and on-site monitoring data show that: the reinforcement steel support system can effectively improve the status of the mining tunnel and limit the plastic deformation of the surrounding soil.Finally, the shield tunnel crossing from the top of the mining tunnel safe, and there are no structural cracks found on the mining tunnel's lining. It show that the construction plan and the corresponding strengthen measures are reasonable, which have certain guidance significance to later similar construction project.