Safety Analysis of a Shield Tunnel Segment with a Cavity behind Lining,Considering the Influence of the Joints
To explore the influence of a cavity on a shield tunnel,a refined numerical model of a shield tunnel,considering ring and longitudinal joints,is established.The variation law of the internal force,deformation,and section safety factor of the segment are investigated under various conditions,such as the depth,area,and location of the cavity.Additionally,the influence of different assembly points of the segment on a tunnel with a cavity behind it is discussed.The results indicate that the order of the adverse effects of cavities at different positions behind the tunnel on structural safety is tunnel waist＞tunnel bottom＞tunnel top.When the cavity area is 5.0 m2,with an increase in the cavity depth,the bending moment and safety factor of the tunnel section at the center of the tunnel top or bottom cavity first decrease and then increase in the opposite direction,and the ellipticity of the segment first decreases to 0 and then increases in the opposite direction.The bending moment is reversed when the cavity depth was 0.3 m or 0.2 m.The safety factor of the section at the center of the left tunnel waist cavity decreases continuously,and the ellipticity of the duct piece and the bending moment increase significantly.When the cavity depth is 0.5 m,the bending moment of the tunnel section at the center of the cavity at the top or bottom of the tunnel is reversed when the cavity area is 3.75 m2.The existence of circumferential joints within the cavity reduces the internal force of the tunnel section at the center of the cavity and improves its safety factor.However,its maximum joint opening is 2.0-3.5 times that of a cavity without a joint.The results provide a reference for the safety evaluation of the cavity behind the lining of a shield tunnel and the selection of assembly points.
rail transitshield tunnelcavitynumerical simulationsafety coefficientinternal force
NETL
NSTL
万方数据
