水压作用对通缝拼装管片结构力学性能的影响研究

以苏通GIL综合管廊工程为背景开展了通缝拼装方式下的原型试验,从水压对管片环的受力、形变及抗裂性方面着手,对通缝拼装条件下水压力对管片结构力学性能影响进行了研究。试验结果表明：①通缝拼装管片结构在拱顶位置出现较大的位移,水压力的增大对管片结构拱顶形变和整体椭圆变形的控制有良好的效果,但管片最大单点位移相比椭圆度更易达到限值;②通缝拼装管片结构建议取单点最大形变率2‰~2.5‰作为形变控制标准;③在高水压作用下通缝拼装管片结构的纵缝张开主要发生在封顶块附近,由于该处纵缝密集、结构刚度最小、变形最大所致,水压力的增大对该处纵缝张开有明显的限制作用,且可减小相应连接螺栓的受力;④水压力的增大会较大幅度地提升管片的抗裂性能,并减小管片主筋的拉应力,但也会使主筋的压应力和箍筋应力有较大幅度的升高;⑤水压力的升高在一定程度上提高了管片结构的受力性能,但高水压使管片结构处于高轴压受力状态,易发生纵缝处的压剪破坏,该破坏具突发性。研究成果对水下盾构隧道的设计具有重要的指导意义。

Water-pressure action on structural behaviors of straight assembling segmental linings of underwater shield tunnels

For Suzhou-Nantong GIL power gallery tunnel, the prototype tests using the straight assembling segmental lining method are carried out. From the aspect of water pressures on the force, deformation and crack resistance of the segmental structure, the influences of water pressures on the mechanical properties of the segmental structure under the straight joint assembling condition are studied. The results show that: (1) The straight assembling segmental lining has a large displacement at the position of dome, and increasing the water pressures can effectively control the dome deformation and the overall elliptical deformation of the segmental structure. However, the maximum single point displacement of the segment is easier to reach the limit than the ellipticity. (2) It is recommended to take the single-point maximum deformation rate of 2‰~2.5‰ as the deformation control standard. (3) Under the effects of high water pressures, the joint opening of the segmental structure mainly occurs near the K-block, which is caused by dense joints, the minimum structural rigidity and the maximum deformation. The increase in the water pressures has a significant limiting effect on the longitudinal joint opening, and can reduce the force of the corresponding connecting bolts. (4) Increasing the water pressures will greatly improve the crack resistance of the segmental structure and reduce the tensile stress of the main reinforcement of the segmental structure, but it will also increase its compressive stress and hoop stress. (5) The increase in the water pressures improves the mechanical properties of the segment structure to a certain extent. However, the high water pressures cause the segmental structure to be in a state of high axial compression, which is prone to crushing and shearing at the joint and the damage is sudden. The research results have important guiding significance for the design of underwater shield tunnels.