Study on Construction Method of the Intersection of the Urban Underground Interchange Tunnel
(1 Powerchina Huadong Engineering Corporation Limited, Hangzhou 311122; 2 Zhengjiang Engineering Research Center of Smart Rail Transportation, Hangzhou 311225; 3 State Key Laboratory of Geohazard Prevention and Geoenvironment Protection, Chengdu University of Technology, Chengdu 610059)
Abstract：
The construction difficulty of an urban underground interchange tunnel is focused on the intersection where two tunnel tubes are incorporated into one-tube tunnel, so the construction is of high risks and the requirements for construction method and technology are rigorous due to multiple conversion of tunnel system modes, such as the super-large section tunnel, the double-arch tunnel and the small-spacing tunnel. Based on construction practice of the underground intersection of Zizhi tunnel in Hangzhou, a construction method and procedure were proposed, namely constructing the large tube from the small tube, then transverse enlarging excavation and finally reverse excavation. The rationality of the proposed construction method was verified by using FEM numerical simulation and monitoring and measuring considering the characteristics of the project. The results show that the construction method of climbing excavation of the adit + transverse enlarging excavation + reverse construction can guarantee the construction safety of tunnel intersection, solve the difficulty excavating from a small tube to a large one; during the construction of the bifurcated tunnel, the tensile stress of surrounding rocks mainly concentrates on the vault,arch bottom and middle rock pillar while the compressive stress mainly concentrates on the middle rock pillar, the haunch of the large arch tunnel and the haunch outside of the small-spacing tunnel; the maximum tensile stress ofthe lining structure occurs at arch bottom and the maximum compressive stress occurs at haunch.
2019, Vol. 56 