Full-scale Experimental Study On Waterproof Performance Of Shield Tunnel Segment Joint

With the quick development of inter-city rapid rail transit and urban subway tunnels,the shield tunnel has gradually become the mainstream construction method in its field.During the continuous maturity of domestic shield tunnel design and construction technology,the shield tunnel is characterized by high water pressure,long distance and large cross section gradually.In order to ensure the safety,durability and usability of the shield tunnel,an important means will be improving the waterproof performance of the tunnel reduces the occurrence of water leakage outside the tunnel.Engineering practice and research show that in the various ways of tunnel leakage,the joint of the segment is the frequent occurrence of the leakage phenomenon in the shield tunnel.At the same time,the tunnel leakage phenomenon and the uneven settlement of the tunnel may lead to series of disasters.Therefore,a clear understanding of the influencing factors for the waterproof performance and failure mechanism of the joints,which could help to improve and optimize the waterproof performance of the joints has become an important way to ensure the long-term operation and safety of the tunnels.Based on the Z2 line project of Tianjin Binhai New Area Rapid Rail Transit,a full-scale test device for the waterproof performance of the shield tunnel segment joints has been developed by the research group to carry out the mechanical compression test and waterproof performance test.And Z2 line waterproof design seal was verified through the above equipment.With the optimized waterproof performance of the gasket and the assembly performance of the tube,the waterproof performance and mechanical compression performance of the two gaskets were analyzed with the compression amount.The advantages and disadvantages of the two different gaskets were evaluated.Besides,the ABAQUS finite element model is established in view of the cross-section form of Z2 line gasket and the optimized seal cross-section.The rationality and feasibility of the model and technical means were verified by the comparison between experimental results and numerical calculation data.With the intuitive numerical calculation,the waterproof failure mode of Z2 type gasket and optimized gasket were analyzed,as well as the compression deformation characteristics of two kinds of elastic gaskets.Finally,the important parameters affecting the waterproof ability of the elastic gasket were studied.The waterproof capacity and closing pressure of different height seals are calculated and analyzed,and the precise range of the maximum and minimum compression ratio of the gasket was derived.The results in this paper show that the optimized gasket could meet the requirements of the pressure for the assembling in design,and the waterproof performance is better than the initial Z2 gasket.Under optimal conditions,the waterproof failure paths of the two type seals are the contact surfaces of the gasket.Under the most unfavorable working conditions,the waterproof failure paths of the two type seals are the contact surfaces of the gasket and the sealing groove.Under the condition of joint without error,the compression deformation of the gasket is up and down symmetrical.In the case of a misaligned joint,the compression deformation of the gasket is centrally symmetrical.After derivation,the maximum compression ratio of the gasket section is accurate to 30%～45%,and the minimum compression ratio is accurate to 20%～30%.