Deformation And Control Of The Cross Tunnel On The Existing Tunnel

With more and more people continually flocking into the bustling cities, the trafficcongestions are more and more serious. Accordingly, traffic tunnels and otherunderground municipal projects are being constructed in a large number. The space ofunderground is limited, while the new tunnel which across existing tunnels areincreasing. Therefore, the construction of the new tunnel will certainly disturb the soilaround it and then change the internal forces and the structure of the existing tunnel.The control mechanism and corresponding specifications of cross-engineering ofexisting tunnel has not been studied systematically at home or abroad.This article took sub line line six which was in Chongqing Yuzhong Two RiversBridge tunnel as background. It analyzed the interaction mechanism of the tunnel withthe existing tunnel, and the importance of mezzanine soil for the cross-buildings. It alsoused the the calculation of finite element numerberical simulations analysises. Themonitoring and meassuring of on-site is also being used. A comprehensive studydisplacement and force of the existing tunnel in underground cut and open-cut space ofsub line six in Yuzhong tunnel was conducted. And the impact on the existing tunnelacross the tunnel parameters were studied and discussed.The main research contents of this paper are as follows:①It summarized and refines a variety of theoretical research construction means ofthe close spaced tunnels.②It analyzed of the mechanism of the interaction of the existing tunnel and thecross tunnel. With reference to the calculation method of the depth of buried rockstress,the importance of laminated soil to cross engineering was defined.③A two-dimensional numerical model of1:1was established in this study, it alsostudied displacement, stress changes and changes in the plastic zone of the supportingstructure (initial support, secondary lining) that the open-cut and underground cutsection of cross tunnel to the existing tunnel. And it also compared stress conditionsof cross tunnel to the existing-tunnel when constructed on the right first and on the leftfirst. It demontrated that there are not any signifficant differences between these twoconstruction methods and the securities of both the new tunnel and the existing tunnelcan be ensured by these two methods.④The key section of subway line six which was located in the lower part of Yuzhong tunnel were monitored (vault settlement, peripheral convergence). Andcompared finite element numerical simulation results with the measurement results, itwas very verified by simulation process and results of numerical this was consistentwith the objective facts.⑤T his research studied the key parametersthat cross tunnel affect the existingtunnel (offset, laminated soil thickness), it also summed up changing law of the lateraloffset and vertical spacing by the affecting degree to the existing tunnel.⑥With the reference to the guideposts to protect the normal operation of theexisting tunnel at home and abroad, and combined with" Design of Concrete Structures”,the author gave some control suggestions for current project and summarized anumber of measures for the protection of existing tunnels in close-spacedconstuctions.