软土盾构隧道横向大变形侧向注浆控制机理研究

注浆是治理软土盾构隧道横向变形等隧道病害经常采用的方法。提出了采用注浆引起的土体体积应变模拟隧道注浆效果的方法,并利用上海地铁隧道注浆加固实践验证了该方法的合理性。利用该方法,以注浆引起的隧道横向收敛、接头张开和错台变化为指标,分析了隧道侧向注浆对隧道横向变形的影响规律,揭示了注浆对隧道横向变形的作用机理;研究了注浆量和注浆范围对注浆加固效果的影响规律。研究发现,注浆能有效改善隧道横向收敛、减小接头张开量。在注浆初期,注浆对隧道横向变形的影响以管片转动为主,该阶段隧道接头张开量减小显著,而隧道收敛减小则相对缓慢;随注浆量的增加,注浆引起的管片运动以刚体平动位移为主,该阶段隧道横向收敛显著减小,但注浆引起的接头错台量和隧道侧向位移则不断增加。最后,以上海地铁隧道为背景,对注浆量和注浆加固范围提出了优化建议。

Effective control of large transverse deformation of shield tunnels using grouting in soft deposits

Grouting is frequently used to control and adjust the large transverse deformation of shield tunnels in clays. However, the grouting is usually performed based on the engineering experience. The control mechanism of grouting for the tunnel transverse deformation is not clear. In this paper, the method to simulate the performance of grouting through the resulted soil expansion is proposed and validated. The effect of grouting on the large transverse deformation of shield tunnels is investigated in terms of the change of tunnel diameter and joint movement using numerical simulation. The optimization is finally carried out through the parametric study. The researches indicate that the grouting can significantly reduce the tunnel transverse deformation and joint opening, and can also produce remarkable joint offset when the volumetric strain of ground caused by the grouting is larger than 3%. The grouting firstly causes rotation and then rigid movement of tunnel segements. Thereafter, the joint opening reduces more significantly due to the segmental rotation at the beginning of grouting. The joint offset increases significantly due to the rigid movement of tunnel segments when more grouting is injected.