基于COMSOL的非饱和土中单桩垂直动力特性研究

Vertical dynamic analysis of the pile in unsaturated soils based on COMSOL

浅层地表存在大量的非饱和土,其动力特性与饱和介质或单相介质相比存在明显的差异,而这部分非饱和土常常是与单桩接触的主要材料,对单桩的动力行为影响显著。该文考虑动力受荷单桩周边土体的非饱和特性,基于非饱和多孔弹性介质的波动方程、单桩运动方程与边界条件,利用多物理仿真软件COMSOL中的偏微分方程模块构建了非饱和土与单桩动力相互作用的数学模型,并考虑土的成层性、横观各向同性和纵向非均质性。在与现有文献对比验证COMSOL模型正确性后,设计多组数值算例,讨论土体饱和度、地层非均质性等因素对单桩垂直动力阻抗的影响。

The groundwater level determines that there is a large number of unsaturated soils on the soil surface,and its dynamic characteristics are significantly different from those of saturated medium or single-phase medium.As the main medium interacting with piles,unsaturated media have a critical effect on the dynamic behavior of piles.In this paper,considering the unsaturated characteristics of the soil around a dynamically loaded pile,based on the wave equation of the unsaturated poroelastic medium,the motion equation of the pile and the boundary condition,the partial differential equation module in COMSOL Multiphysics software was used to establish a dynamic mathematical model of the interaction between the pile and the unsaturated soil with complex characteristics,such as stratification,transverse isotropy,inhomogeneity and so on.Meanwhile,several complex characteristics of soils and piles can also be reflected in this model.After verifying the correctness of the COMSOL model by comparing with existing literature,a series of numerical examples were designed to discuss the influence of factors such as the soil saturation and inhomogeneity on the vertical dynamic impedance of a pile.