Abstract:

Joint is the main part where leakage occurs in shield tunnels, and the waterproofing of the joint surface is the key of the waterproofing of shield tunnels. The waterproofing of the joints of shield tunnels depends on the compression of the water sealing materials on the contact surface of the joints under the action of the contact pressure. However, the contact pressure is influenced by the dislocation and opening of the joints. Regarding GPST ( Ground Penetrated Shield Technology) applied in the construction of Nanjing Metro, the shield is boring under supershallow soil cover or even without soil cover, the thrust force of the cylinders is inadequate, which results in insufficient compression and compactness of the water sealing strips. Tests and simulations are made in order to solve the abovementioned problems and water sealing strips with low hardness and high porosity suitable for segments under shallow soil covers are developed. The waterproofing tests on the water sealing strips developed demonstrate that the water sealing strips developed can meet the longterm waterproofing requirements of the segments of the mentioned project.

Key words: shield tunnel, GPST method, joint waterproofing, property of water sealing strip