Full-scale experiment for segmental linings of deep-buried shield tunnels bearing high inner water pressure: Comparison of mechanical behaviors of continuous- and stagger-jointed structures

Full-scale loading tests were performed on shield segmental linings bearing a high earth pressure and high inner water pressure, focus-ing on the effects of the inner water load and assembly manner on the mechanical properties of the segmental linings. The test results indicate that the deep-buried segmental linings without inner pressure have a high safety reserve. After the action of high inner water pressure, the lining deformation will increase with the reduction of the safety reserve, caused by the significant decrease in the axial force in the linings. Because the bending moment at the segmental joints is transferred to the segment sections in the adjacent ling rings, the convergence deformation, openings of segmental joints, and bolt strains are smaller for the stagger-jointed lining than those for the continuous-jointed lining; however, dislocations appear in the circumferential joints owing to the stagger-jointed assembly. Although it significantly improves the mechanical performance of the segmental lining, stagger-jointed assembly results in compromising the water-proofing safety of circumferential joints. The stagger-jointed assembly manner can be considered to improve the service performance of shield tunnels bearing high inner water pressure on the premise that circumferential joint waterproofing is satisfied.