Experimental study on performance of shield–reinforced steel fiber concrete double-layer linings under internal water pressure

Based on the prototype of shield-reinforced steel fiber conducted double-layer linings with the scale of 1∶1, model tests of deformation laws and failure under high internal water pressure are conducted. The test results show that the segmental joints are the tensile weak positions of double-layer linings, and the cracks occur in the inner lining near the joints firstly and then are evenly distributed along the circumferential direction. The failure process of the double-layer linings can be divided into four stages: (1) At the linear elastic stage, the stress and deformation of the linings change linearly with the increase of the internal water pressure. (2) At the cracking stage of the linings, the steel fiber plays a bridging role, the stiffness of the linings gradually decreases, the proportion of internal water pressure shared by the segmental linings gradually increases, and the axial force of the linings is gradually transferred to the reinforcing bars. (3) At the stable stage of cracking of the linings and the damaged stage of the joints, the residual stiffness of the inner linings tends to be stable, and the proportion of the internal water pressure shared by the segmental linings no longer increases, and then the concrete of some segmental joints is damaged, and the tensile stiffness of the segement decreases. (4) At the failure, the stresses of stage of the linings gradually reach the yield value, and eventually the severe damage of segmental joints occurs. The experimental results reveal the failure process of the double-layer linings subjected to internal water pressure, and they can be referred to for the engineering application.