南通富水砂层盾构隧道开挖对邻近桩基影响分析

为有效控制盾构隧道近距侧穿既有桥梁桩基施工,给桩基造成一定安全风险,本文依托南通地铁1号线区间盾构工程,建立三维有限元模型,基于流固耦合理论分析盾构施工对桩基水平位移、内力、地表沉降的影响,并验证计算的准确性。结果表明:盾构开挖面距离桩基2D范围内,盾构施工对桩基产生的影响占总水平位移的85%;桩基产生的最大水平位移为16.13 mm;盾构施工引起桩基剪力和弯矩的变化量明显。在富水砂层类似工程施工中应加强监测,同时采取优化盾构掘进参数和地层加固等措施,减小盾构施工对桩基影响。

Analysis on influence of shield tunnel excavation in Nantong water-rich sand stratum on adjacent pile foundations

In order to effectively control the safety risk of pile foundations caused by the construction of shield tunnel side-crossing the existing bridge pile foundation at close distance,relying on the interval shield engineering of Nantong Metro Line 1,a three-dimensional finite element model was established.Based on the theory of fluid-solid coupling,the influence of shield construction on the horizontal displacement,internal force and ground settlement of the pile foundations was analyzed,and the accuracy of calculation was verified.The results showed that the distances between the shield excavation surface and the pile foundations were within 2D,and the influence of shield construction on the pile foundations reached 85%of the total horizontal displacement.The maximum horizontal displacement of the pile foundations was 16.13 mm.The amount of change in the shearing force and bending moment of pile foundations caused by shield construction was obvious.During the construction of similar projects in the water-rich sand stratum,the monitoring should be strengthened,and the measures such as the optimization of shield tunneling parameters and ground reinforcement should be taken to reduce the influence of shield construction on the pile foundations.