Stress and deformation properties of shield segmental linings under internal water pressures

The mechanical responses of continuous- and stagger-jointed shield lining structures with different buried depths and internal water pressures are investigated, and then the influences of the internal pressure, buried depth and lining assembly manner on the stress and deformation properties of shield segmental linings are analyzed. The results show that the deformations of the shield lining rings increase, and the change of the internal forces presents the characteristic of three stages in the process of inner water inside the tunnel from the empty pipe state to the full one. The first stage is from the empty pipe state to the half one, in which the bending moments and axial forces of the lining rings increase and decrease, respectively, but the change ranges of the bending moments and axial forces are very small. The second stage is from the half pipe state to the full one, in which the bending moments and axial forces of the lining rings increase and decrease, respectively, and the change range of the axial forces is less than that of the bending moments. The third stage is the increase of the internal pressures after the pipe is full, in which the bending moments and axial forces of the lining rings decrease at the same time, but the reduction of the axial forces is much greater than that of the bending moments. The internal forces and deformations of the lining structures reduce with the decrease of the buried depth, but the local joint opening and bolt stress may increase in the shield segmental linings under the internal water pressure. Thus, enough attention should be paid to the safety reserve of the joints in the linings with shallow buried depth. In addition, under the same buried depth at tunnel top and internal water pressure inside the tunnel, the convergence deformation, local joint opening and stress of the bolts at the joint positions of the staggered-jointed lining structures are better than those of the continuous-jointed ones, which means the staggered-jointed assembly manner should be preferred for the shield linings under the internal water pressures.