Abstract：Aiming at the argument that whether the large pipe roof or small pipe roof should be adopted in the construction of shallow-buried tunnels in soft ground，the function mechanism of pipe roof is analyzed and the requirements for‘shed’and‘frame’to developed on the tunnel arch are put forward based on the in-situ measurement in Jiefang Road Tunnel in Hangzhou City and centrifuge model tests. According to the theory of shed and frame，it is pointed out that pipe roof can consolidate the ground and disperse the ground stress and reduce the excavation release stress. It was demonstrated that，in the pipe roof and grating system，the pipe roof can disperse the ground stress and the grating is load-bearing body based on the 3D FEM analysis of one underground passage located in Shanghai. The design and construction parameters for the three kinds of the pipe roof systems are also put forward. The pipe roof system can be divided into three kinds according to the pipe diameter，namely small pipe roof，medium pipe roof and large pipe roof.
