Abstract: For the construction of urban water conveyance underground shield tunnels under high internal pressure, we propose a separate lining structure of self-compacting concrete (SCC)-lined steel pipe, and present an in-situ experiment on this new structure for exploring its deformation behaviors that was conducted in the test section of a water resources allocation project in Pearl River Delta. Flexible capsules are used to simulate the high internal pressure in the tunnel; the testing technology of fiber Bragg grating and distributed optical cables used to monitor the structure deformation. The results show that as the internal pressure increases, the deformation in the segment, self-compacting concrete, and steel pipe are increased gradually; the strain distributions at the concrete’s inner arc surface and the segment’s arc surface are more uniform than those at the concrete’s outer arc surface. The composite drainage plate can effectively separate the segment and the self-compacting concrete. The deformation in the steel pipe manifests characteristics of overall tension and local bending, and is significantly affected by internal pressure.

Key words: water conveyance tunnel, steel tube linings, separate bearing structure, in-situ test, deformation law