二维饱和土体动态孔隙率及相关动力响应特性研究

饱和多孔介质的动力响应研究在众多工程领域具有重要意义。充分考虑孔隙率的变化规律与影响因素，有利于合理揭示饱和多孔介质的相关力学行为。为此，将动态孔隙率模型与用于表征饱和多孔介质动力特性的u-U-p型方程结合，构建相应的非线性力学模型，利用Comsol Multiphysis PDE求取相应的数值解，以此研究不同透水条件下，受谐波载荷激励的二维饱和土体的孔隙率、变形量及孔隙水压力的变化规律。结果表明：孔隙率的变化与土骨架的体应变及孔隙水压力直接相关，土体压缩过程中，孔隙率相应减小，土骨架与孔隙流体的相互作用增强，土体运动时所受阻力增大，其无量纲竖向位移小于孔隙率被视为常数时的情况，在此条件下，由于土体的变形量减小，其孔隙水压力也相对减小。故充分考虑动态孔隙率，有利于更加精确地研究等饱土体和多孔介质的相关力学行为。此外，土体上表面透水条件下，孔隙流体可以从土体表面自由排出，土骨架承受的载荷更大，与不透水条件相比，土体孔隙率、竖向位移、孔隙水压力等变化更为显著。

Dynamic porosity and related dynamic response characteristic of two-dimensional saturated soil

Dynamic response of saturated porous medium is of great significance in many engineering fields. The consideration of varying porosity helps to reasonably reveal the related mechanical behavior of saturated porous medium such as soil. Dynamic porosity model is combined with u-U-p equation representing the dynamic characteristic of saturated porous medium. And a new nonlinear dynamic model is established. Comsol Multiphysics PDE is used to obtain its numerical solution. On this basis, the change of porosity, deformation and pore water pressure of two-dimension saturated soil are developed under two different kinds of permeable conditions and excited by harmonic load on the surface. The result shows that the porosity relates directly to the volumetric strain and pore water pressure of soil. The loading process decreases soil porosity, and enhances the interaction between solid skeleton and pore fluid increases, therefore increases the resistance applied on solid skeleton. The dimensionless vertical displacement and pore water pressure are also low under constant porosity condition. It is useful to increase the research rationality of mechanical behavior of saturated porous medium such as soil if the dynamic porosity is considered. On the other hand, pore fluid can discharge freely from permeable top surface. So, the load that is born by soil skeleton is greater, the porosity, deformation and pore water pressure are also greater comparing with the condition under impermeable top surface .