盾构近距离穿越大型立交桥超长桩基础会对桩基础及上部桥梁结构产生不利影响。通过对盾构近距离侧穿超长桩基础过程进行数值模拟,研究了不同深度处盾构掘进对超长桩承载性状、变形和内力的影响。研究表明:盾构近距侧穿超长桩会导致桩身出现较大变形及内力,且隧道轴线与超长桩处于不同相对位置时会对桩的特性产生不同影响。其他条件不变时,盾构从桩身上部的近距离穿越,将引起桩身最大的横向水平位移;盾构从桩身中部近距离穿越则将引起桩身产生沿盾构掘进方向的最大的水平位移;盾构从桩端附近穿越时将引起桩身产生最大的竖向位移;盾构从桩身中下部穿越时将引起桩身产生最大的附加轴力。桩身侧阻在隧道轴线附近呈“S”型,同时桩身轴力最大值也出现在隧道轴线附近。盾构导致桩身产生纵向和横向变形延伸至桥面高度的变形量相当可观。当盾构穿越高架桥梁基础时应该严格控制桩顶水平位移。
Shield tunneling passing through adjacent large interchange's super-long piles has negative effect on super-long piles and bridge structures. Numerical analysis is conducted to simulate the process of the shield tunneling passing through the adjacent super-long piles. The bearing performance, deformations and forces of super-long piles caused by the shield tunneling with different depths are investigated. Some conclusions are drawn as follows. Large deformations and forces may occur in piles due to nearby tunneling. The various tunneling locations have different influences on the behaviors of piles. The most unfavorable position for lateral displacement is the upper part of pile;the most unfavorable position for longitudinal displacement is the middle part of pile;the most unfavorable position for vertical displacement is the tip of pile;the most unfavorable position for additional axial force is the lower part of pile, when other conditions are the same. The shaft resistances appear ‘S-shaped’ distribution near the tunnel axis;meanwhile, the maximum axial forces of the piles are also located at the tunnel axis. Lateral and longitudinal deformations of piles that extend to bridge decks are considerable. Horizontal deformations of piles top should be strictly controlled while tunneling passing through adjacent interchange's super-long piles.