Experimental Research On Large Section Subsea Tunnel Segment Joint Waterproofing

With the shield method in tunnel construction has been used more and more widely, "long, large and deep" has become the trend of the development of shield tunnels in China, especially the rise of the subsea tunnel, shield tunnel construction is facing the environment becomes more and more complex.Based on the background of Shantou su’ai channel project, through the comparative study of domestic and foreign large section underwater shield tunnel, the research and test analysis are mainly carried out about the shield segment joints waterproof mechanism, waterproof road number, material of rubber gasket, Rubber gasket-section and segment size of groove, the basic properties of the rubber gasket material, compressive properties, waterproof ability,durability and so on. The main contents and conclusions are as follows:(1) Studied how to meet the needs of the shield tunnel waterproofing in Suai undersea shield tunnel, including water channel number, rubber gaskets, rubber gaskets and pipe-section sheet groove dimensions. Finally determined to use single-channel EPDM gaskets and arrange water swelling rubber seal on the outside of segment joints trench.(2) Tested the basic properties of rubber gasket materials, assembly stress, the waterproofing ability of the T-style located at the intersection of the longitudinal and circumferential joint. The test results show that the rubber sealing pad offset of shield segment assembly stress and the effect of compression performance is smaller; The waterproof ability of the elastic rubber sealing gasket is proportional to the assembly stress, and the ratio coefficient decreases with the increase of the seam opening amount.(3) Tested the stress relaxation after the EPDM elastic rubber gasket material was aged and used the "P-T-t" three element model, the stress retention rate after one hundred years was predicted. In the normal servicecondition of Suai subsea tunne, after 100 years, the stress retention ratio of EPDM elastomeric gasket located at shield segment joints.