Prototype Loading Tests on the Mechanical behaviors of the Shield Lining Structure of a Water Storage and Sewage Tunnel

Abstract: A sophisticated and flexible testing system that can simulate both external water-soil pressures and inner water pressure was designed, based on which both single-ring and three-ring full-scale loading tests were conducted, and some interesting observations were made: increasing inner water head decreased the axial force, which thereby increased the lining deformation; the bending moment transferring mechanism was evident in the three-ring tests due to staggered fabrication, which significantly reduced the structural deformation comparing with the single-ring tests; the structural deformation accumulated slightly during the water inflow and drainage cycles, and the structural deformations remained stable after nine loading cycles; the internal forces increased and convergence deformations decreased as hoop effect was caused by the uniformly distributed grouting pressures; both the cracking process captured by DIC technique and measured overall deformations showed that the lining structure failed when the inner water head exceeded 65m (ultimate limit states) .