| The construction of underwater shield tunnels in our country is developing in the direction of large diameter,deep burial,high water pressure,and complicated geological conditions.The importance of segment joint waterproofing is becoming more and more prominent.However,the waterproof system of traditional single sealing gasket has been difficult to meet the requirements.Although the double sealing gasket waterproof system has been used in some high-water-pressure shield tunnel,it still strongly relies on the engineering analogy method to complete the design.Its waterproof mechanism,waterproof performance and other aspects are not yet clear,and a complete design method about double sealing gasket waterproof system have not yet been formed.Based on the project of Jiangyin Jingjiang Yangtze River Tunnel and the Jintang Subsea Tunnel of the Yongzhou Railway,the waterproofing mechanism,waterproofing performance and design method of double gasket waterproofing system for shield tunnel under high water pressure were deeply studied by means of data investigation,numerical simulation and waterproofing test.The main research work and research results are as follows:(1)The numerical simulation methods of sealing gasket waterproofing in engineering are summarized and the advantages and disadvantages of each scheme are compared.The compression process of segment joint gasket in shield tunnel was numerically simulated by using finite element method.On this basis,the coupled EulerianLagrangian(CEL)method was used to simulate the leakage failure process of the double sealing gasket waterproof system.The seepage process of water in the shield tunnel double gasket waterproof system is obtained,and the failure mechanism of double gasket waterproof system is revealed.(2)Waterproofing tests of double gasket and corresponding single gasket were carried out under the most unfavorable design conditions.Through the comparison of the water pressure time history curve and the permeating phenomenon of the two in the experiment,the correlation between the waterproof capacity of the double sealing gasket waterproof system and the waterproof capacity of the single sealing gasket is obtained.(3)Waterproofing tests of double-channel gasket under different opening and different staggered platform quantities were carried out,and the influence rules of opening and staggered platform quantities on the waterproofing capacity of doublesealing gasket system were obtained.Based on the test results of double gasket waterproof system and the simulation results of seepage,the waterproofing mechanism of double gasket waterproof system is revealed.(4)According to the waterproofing mechanism and failure mechanism of double sealing gasket waterproofing system,the engineering design idea and flow chart of double sealing gasket waterproofing system are put forward.In this paper,the waterproof system of double sealing ``gasket is designed for the Jintang Subsea Tunnel of the Yongzhou Railway.Several design schemes are given,and the selection of each scheme is carried out through waterproof test. |
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