软土盾构超近距侧穿桥墩桩基的变形传递分析

依托于某盾构连续穿越高架桥工程,利用有限元数值模拟研究盾构超近距离穿越对高架桥墩的影响,并从结构变形传递角度揭示其倾斜机理,最后结合实测对施工控制效果进行总结。研究结果表明:(1)盾构穿越时,墩身沿高架桥方向的倾斜(纵向倾斜)向远离隧道方向逐渐增加,而垂直于高架桥方向的倾斜(横向倾斜)则沿盾构掘进的反方向先增后减;(2)盾构穿越地层的扰动经由桩基变形传递至上部的桥墩及道面,墩身的纵向倾斜主要由上部道面约束导致墩顶、墩底水平位移相差较大引起,而横向倾斜主要由下部桩基沉降不均导致承台倾斜所引起;(3)在施工控制下,桥墩实测纵向倾斜最大值不超过0.4‰,横向倾斜最大值不超过0.2‰。

Deformation Transmission Law between Pier and Pile of Viaduct Caused by Adjacent Shield Tunneling in Soft Ground

Based on a certain project of shield crossing viaduct piers, pier responses caused by shield tunneling were studied through finite element numerical simulation, and mechanisms of viaduct pier inclination were clarified in the prospective of structural deformation transmission. Furthermore, the construction control and its effect were summarized with field measurement. The results indicate that: (1) When shield passing by, the inclination of the pier along the viaduct (longitudinal inclination) gradually increases away from the tunnel, while the inclination perpendicular to the viaduct (transversal inclination) increases first and then decreases in the opposite direction of the shield tunneling; (2) disturbances caused by shield tunneling through the ground are transmitted to the upper pier and pavement via pile deformation. The longitudinal inclination of the pier is mainly caused by the differential horizontal displacement of the top and the bottom of the pier, which is caused by the upper constraint of the pavement. The transversal inclination is mainly caused by the inclination of piles cap due to the uneven settlement of piles; (3) under the control of construction, the maximum longitudinal inclination of the pier is lower than 0.4 ‰, and the maximum transversal inclination is lower than 0.2 ‰.