考虑桩周土竖向作用和施工扰动效应时大直径楔形桩的纵向振动特性

Vertical vibration characteristics of a large diameter tapered pile considering vertical action of surrounding soil and construction disturbance effect

将桩土系统划分为数量足够多的微元层,基于复刚度传递多圈层平面应变模型,求得了桩侧土对桩身的剪切刚度。采用Voigt体模拟桩周土与相邻微元桩段交界面上环形截面的作用,求得了弹簧和粘壶系数。通过拉普拉斯变换,结合相邻微元桩段交界面上的位移连续和应力平衡条件,得到了修正的阻抗函数递推法。通过求解微元桩段的动力平衡方程,结合修正的阻抗函数递推法,求得了桩顶的阻抗函数。将该解与已有解进行对比,进一步验证了的楔形桩承载性能的优越性。在桩基动力设计所关心的低频范围内,通过参数分析研究了桩周土的竖向作用与施工扰动效应的耦合作用。

Discretizing a pile-soil system into many enough micro-element spheres,based on the multi-sphere planar strain model for complex stiffness transfer,the complex shear stiffness of the surrounding soil to the pile was derived. The vertical action of the surrounding soil on the adjacent pile micro-elements' interface annular sections was simplified as a Voigt model,its spring and damper coefficients were derived. Then through Laplace transformation,combining the displacement continuity conditions and stress equilibrium ones on interfaces of adjacent pile microelements,the amended impedance function transfer method was deduced. Through solving dynamic equilibrium equations of pile micro-elements,combining the amended impedance function transfer method,the impedance function at the pile top was obtained. By comparing the solutions gained here with the published ones,the advantages of a tapered pile's loadbearing ability were verified. Finally,a parametric analysis was conducted to study the interaction between the vertical action of surrounding soil and construction disturbance effect in low-frequency range. The results provided a guiding for aseismic design of pile foundations.