Research On Construction Mechanics And Ground Surface Settlement In Turn-Round Track Metro By Tunnelling Machine

At present the rapid development of metro transport in our country incurred the accumulation of metro construction and technological development. The turn-round track were not only composed of large cross-section tunnel and all kinds of tunnels, but also the tunnels were made up tunnel group. It is important to insure the safety and minimize the impact on surrounding while excavating the turn-round track by suing the subsurface excavation method in city. It is necessary to carry out the research on metro construction.Large cross-section interval tunnel next to Donghu station in Guangdong metro 6 line was the engineering background. The 2-bench tunnelling method was adopted according to the soft and crack stratum of tunnel. Upper bench was constructed with tunnelling machine and bottom bench was constructed wtth drilling and blasting method. Bench tunnelling method was used to reduce the ground settlement during drilling and blasting.Large cross-section tunnels were treated as target for analysis. Optimizing design proposal was proposed and reasonable sequence of construction was determined by dynamic simulation on sequence of excavation and effort of support. All of these were done to insure the safety of building on earth during construction of tunnel.The typical ground surface settlement curve of tunnel was determined by using compute to simulate and analysis three-dimensional dynamic construction on research subject. The ground surface settlement was strictly controlled by choosing the optimization construction scheme, improving reinforced area and optimizing structure designed parameters of tunnel.In the process of the tunnel excavation, the epaulement and the podium of the tunnel bear biggish stress, and there will obviously appear the phenomenon that the stress concentrate in the comer of the tunnel. In the process of the construction it is must reinforce the surveillance and measure to these parts which are disadvantageous to the structure stabilization of the tunnel. Under the condition of necessity, it is must increase the rigidity and intensity of the reinforced region and enhance and improve the designed parameters of the tunnel structure properly.Setting the inverted arch has important function to the whole stability of the tunnel structure, and it not only enhanced the safety of the tunnel construction, but also extend the wear of the tunnel's use over along period of time. In the progress of the tunnel's construction, it must construct the inverted arch in time, and close the shoring wreath as early as possible.