饱和土中单桩水平瞬态响应研究

基于Biot动力固结方程，应用Novak薄层方法研究了饱和土中单桩在水平冲击荷载作用下的动力响应问题。首先引入势函数对方程解耦，再通过算子分解和分离变量法，结合初始边界条件，并联立桩基振动微分方程，推导了Laplace变换域内桩身位移函数及内力表达式。采用Laplace逆变换的优化模型求得了时域内瞬态响应的封闭解。将该解退化到单相介质条件下的桩顶位移-时间曲线与已有的边界元方法的结果基本吻合，验证了解答的正确性。参数分析结果表明：桩-土模量比、长径比、渗透系数对桩身位移均影响显著，而同条件下长径比超过一特定值后则影响较小，且桩土模量比是影响桩身弯矩大小及其分布的重要参数。

Transient response of single pile under horizontal load in saturated soil

Based on the Biot's consolidation equation, transient response of single pile embedded in isotropic saturated soil under horizontal loading is investigated by applying Novak's thin layer method. The potential function is introduced to decouple the governing differential equation, then by means of differential operator splitting and variable separation method coupled with lateral vibration differential equation of pile foundation, the expression of the horizontal displacement and the internal force of the pile in Laplace space is obtained. The closed solution of displacement of the pile is calculated by using an optimal model of numerical inverse Laplace transforms. When the soil is reduced to the single medium, the good agreement is found in the comparison between the calculated data and that of previous made by boundary element method, so as to verify the correctness of the method. Parametric studies have been carried out; and it is found that the influences of pile-soil modulus ratio, pile slenderness ratio and permeability are significant, but the effect is limited when the slenderness exceed a certain value. Besides, pile-soil stiffness ratio pays a critical role in bending moment and its distribution.