Theoretical And Experimental Research On Subway Station Structure By Expansion Of Parallel Shield Tunnels

For the sake of controlling the construction of parrelled shield tunnels and subway station,to reduce the non-promotion operation in shield construction and enhance the utilization efficiency of shield machine,the structure construction scheme of excavating double subway station has been presented,which include construction processes of shield tunnels,cross-channels,braced-frame and so on.The numerical simulation,theoretical derivation and node tests are occupied to conduct research work in this paper.The main works and results are as follows:1)Based on literature information of constructing metro station by expansion of parallel shield tunneling at home and abroad,a double-storey subway station of frame structure was developed.The running tunnel was outside the mainbody of the station.The station was constructed by combining two parallel shield tunnels and PBA method.The mechanical behavior of the structures and key nodes during the process of construction were studied by numerical simulation.The results show that the force of node between segment and wall column is large.The station can meet the requirements of the structural force during construction.During the construction of cross tunnel and arch lining,a large surface settlement can be observed.2)The static model tests of 1:1 scale nodes were conducted.The deformation,force and damage patterns of the nodes under the horizontal and vertical loads were studied.The failure criteria and determination of limit bearing capacity of the nodes under normal operation were put forward.The results indicate that the joint connection method of embedding steel has greater rigidity and load ability than the embedding connector.The main damage form of both nodes are concrete crush at the bottom.3)The mechanical properties of the nodes included cracking development and bending performance were studied by analytical solution.The results indicate that,the joint connection method of embedding steel has greater bending stiffness than the joint connection method of embedding connector.Howere,the deformation magnitude of the embedding steel node increases not obviously and brittle failure of the steel node is easy to happen.The calculated curves of bending rigidity are more suitable to the joint connection method of embedding connector.4)Dynamic performance of the nodes were studied by quasi-static tests.Failure pattern,hysteretic characteristic,skeleton curves,ductility performance and energy dissipation capacity of the nodes were studied.The results show that hysteresis behavior of the nodes are similar.The segment separated from the wall column when the embedding steel node is failure and the segment slips down along the node when the embedding connector node is failure.The degraded speed of stiffness of the embedding steel node is slower and the energy dissipation capacity of the embedding connector is stronger.The structure and construction scheme of expansion subway station under parrelled shield tunnels meet the requirement of planning construction of the subway station structure and the interval tunnel and enhance the utilization of shield machine.According to the results of numerical simulation,theoretical derivation and node tests,it can be know that the structures and key nodes are safe and reliable during construction.The strength and stability of the structures can meet the requirement in the construction and design.