砂卵石地区盾构下穿某拱肋梁桥数值分析

NUMERICAL ANALYSIS OF SHIELD UNDERPASSES AN ARCH RIBBED GIRDER BRIDGE IN SANDY COBBLE AREA

地铁盾构隧道下穿城市桥梁不可避免的产生一定的扰动,而砂卵石地层含水率高灵敏度高地层粘聚力小等工程性质又增加了桥梁沉降变形控制的难度。文中基于成都市某地铁工程,探讨砂卵石地区盾构下穿城市拱肋梁桥的加固设计,借助有限元软件模拟预加固措施及盾构掘进过程,分析了在采取预加固措施条件下盾构掘进对桥梁产生的影响。预加固措施宜选择安全可靠、变形控制好、地层适应性强的措施,如超前大管棚支护、大刚度抗滑移桩及袖阀管注浆等。计算结果表明,采取以上措施能够将拱肋梁桥的沉降变形控制在允许范围之内。

The shield tunnel of metro crossing the urban bridge inevitably cause some disturbance. The engineering properties of sandy cobble stratum, such as high water content, high sensitivity, and low cohesion of stratum, increase the difficulty of bridge settlement and deformation control. Based on a metro project in Chengdu, this paper discussed the reinforcement design of the arch ribbed bridge under shield tunneling in sandy cobble area, and analyzed the influence of shield tunneling on the bridge under the condition of the pre-reinforcement measures and the shield tunneling process by using the finite element software. The pre-reinforcement measures should be safe and reliable, with good deformation control and strong adaptability to the stratum, such as advanced large pipe shelter support, large stiffness anti-slip pile, and sleeve valve pipe grouting. The calculation results showed that the settlement deformation of the arch ribbed bridge can be controlled within the allowable range by the above measures.