ABSTRACT
With tunnel boring machine (TBM) technology development, tunnels are being constructed even in challenging environments. Nevertheless, there is still a problem in that excessive stress is induced in the segmental lining during shield TBM tunnelling in overstressed rock. Structural solution based on the resistance principle causes overdesign of segmental lining and increases direct construction cost. Therefore, studies on various deformable supports that allow some tunnel wall displacement after excavation to reduce the support pressure have been conducted based on the yielding principle. In TBM tunnelling, the pre-fabricated composite segments with a compressible layer combined at their extrados can be considered, but this design is not well established. In this study, a numerical analysis based on the finite element method was performed to investigate the effect of the compressible layer on the segmental lining and the surrounding ground in the deep soft rock.
