基于广义剪切位移法的桥梁桩基长期沉降分析
Long-term settlement of pile foundation of bridges based on generalized shear displacement method
-
摘要: 根据 桥梁群桩基础的变形特征,将承台、桩和土体三部分作为一个共同作用的系统。假设桩土界面上的应力和变形协调,考虑桩周和桩端土体的线黏弹性性质,通过对典型单元体的分析及弹–黏弹对应原理的应用,推导了桩顶沉降在 Laplace 变换域的解析表达式,再由 Schapery 数值反演方法得到了桩顶沉降在时间域的数值解。将沉降分析的结果与有限元方法计算结果进行对比,二者基本一致,说明该方法的合理性及应用价值。将单桩沉降通过计入桩的存在对土体的“加筋效应”的桩间相互作用系数进行群桩作线性叠加,求得 了桥梁群桩基础沉降量随时间的发展变化。最后,将该分析方法应用于泰州长江大桥桩基工程实际,对工程设计有一定的指导意义。Abstract: Based on the deformation characteristics of pile group foundation of bridges, the interaction system is divided into three parts, pile cap, piles and soil. It assumes the compatibility of stress and deformation on the interface between the piles and the soil which present linear viscoelastic characteristics. Through the analysis of typical elements and the application of elastic-viscoelastic correspondence principle, a formula on pile settlement in Laplace transform domain is derived. After that, the numerical solution in time domain is derived by using the Schapery numerical inversion method of the Laplace transform. It is demonstrated that the solutions of pile settlement are in accordance with those of the finite element method. So the proposed method is rational and practicable. Based on the interaction coefficient which considers the “reinforcing effect” (owing to the presence of piles), the linear superposition of single pile settlement is carried out. Thus, the relationship between bridge pile group settlement and its variation with time is obtained. Finally, the proposed method is applied in pile settlement analysis of Taizhou Yangtze River Bridge, and it can provide guiding significance for the related engineering design.