The present study proposes a closed-form solution of flexible combined pile-raft foundation (CPRF) resting on an elastic medium under dynamic loading. Two components of the foundation system, i.e. pile and raft are idealized as beam and plate, respectively, resting on an elastic two-parameter Pasternak soil medium. The governing differential equations of these components under horizontal harmonic loading is formulated and the subsequent closed-form solutions of the same are obtained by using Fourier transformation technique. Two simultaneous analyses are performed for piles and raft and displacement compatibility is satisfied at the junction of the components. The proposed method is validated with dynamic centrifuge test results, available in the literature. In further parametric studies, the effect of loading frequency on the dynamic displacement response of CPRF is investigated. Also it is perceived that with an increase in raft flexibility by 60%, the horizontal load sharing proportion of raft reduces by 75%–65% for loose to dense sands, correspondingly. This study contributes significantly in understanding the steady-state response of CPRF under dynamic loading from an analytical perspective.

本研究提出了一种在动态载荷下置于弹性介质上的柔性组合桩筏基础（CPRF）的封闭形式解决方案。基础系统的两个组成部分，即桩和筏，分别理想化为梁和板，分别位于弹性的两参数Pasternak土壤介质上。公式化了这些分量在水平谐波载荷下的控制微分方程，并利用傅立叶变换技术获得了这些分量的后续闭式解。对桩和筏进行了两个同时分析，并在组件的交界处满足了位移兼容性。动态离心机测试结果验证了该方法的有效性，该结果可在文献中找到。在进一步的参数研究中，研究了加载频率对CPRF动力位移响应的影响。另外，人们认为，随着筏柔性的增加60％，从松散到稠密的沙子，筏的水平载荷分担比例相应地降低了75％–65％。这项研究从分析的角度为理解CPRF在动态载荷下的稳态响应做出了重要贡献。