Abstract:

HongLaoShai section of line 3 of Shenzhen Metro is a long smallspaced verticaloverlapped shieldbored tunnel. The scheme that "the lower tunnel is constructed in ahead of the upper tunnel" is adopted on basis of the 3D numerical simulation results. The key technical measures taken in the construction of the tunnel, including the control of the tunnel boring, the grouting consolidation of the soils between the lower tunnel and the upper tunnel and the bracing of the lower tunnel by means of temporary support trolleys, are focused. The monitoring records indicate that the measures taken are effective and sucessful. The paper can be served as reference for the design and construction of similar overlapped tunnels in the future.

Key words: small spacing, long distance, overlapping tunnel, grouting consolidation, support trolley, construction technology