盾构隧道施工对桩基沉降影响的简化计算

Simplified Calculation on Influence of Shield Tunneling on Settlement of Pile Foundation

摘要:

随着城市化的深入发展，城市内隧道施工频繁涉及近距离穿越桥梁桩基的情况，这就要求评估隧道穿越对桥梁桩基的影响。然而，当前的研究方法虽科学严谨，但对于工程设计人员来说，可操作性不强。针对这一问题，结合美国API规范与《建筑桩基技术规范》（JGJ 94—2008），创新提出一种理论算法，旨在为工程设计人员提供一种相对便捷的桩基沉降计算方法。新方法通过分析盾构开挖引起的土体自由场位移以及桩土荷载传递机理来计算盾构施工引起的桩基附加轴力，并据此进一步计算桩基沉降量。经过与数值模拟结果的对比验证，该方法被证明是合理有效的。利用该方法，工程技术人员能在项目初期阶段有效预测桩基受影响程度，从而为后续工程方案的制定提供科学指导。

Abstract:

With the deep development of urbanization, the tunnel construction in cities frequently involves the close crossing of bridge pile foundations, which is necessary to evaluate the impact of tunnel crossing on bridge pile foundation. However, the current study methods are scientific and rigovous, but the operability is not strong for the engineering designers. Aiming at this problem, combined with the American API standards and Technical Code for Building Pile Foundations (JGJ 94—2008), a theoretical algorithm is innovatively put forward in order to provide a relatively convenient method for calculating pile foundation settlement for the engineering designers. The new method computes the additional axial force of pile foundation caused by the shield construction through the analysis of free field displacement of soil caused by shield excavation and the load transfer mechanism of pile and soil. And accordingly, the settlement of pile foundation is further calculated. Compared with the numerical simulation results, the proposed method is proved to be reasonable and effective. The engineering technicians can effectively predict the impact on pile foundations at early stage by this method so as to provide the scientific guidance for the formulation of subsequent engineering schemes.