饱和多孔黏弹地基热-水-力耦合动力响应分析

天然土体由于沉积条件和应力状态不同, 往往会表现出一定的流变性. 本文研究地基上表面受外载荷作用时, 渗透系数和孔隙率变化对饱和多孔黏弹性地基热-水-力耦合动力响应问题的影响. 基于Biot波动方程、达西定律和Lord-Shulman广义热弹性理论, 并引入了考虑黏弹性松弛时间因子的Kelvin-Voigt黏弹性模型研究地基上表面受热/力源作用时, 孔隙率和渗透系数变化对均质各向同性饱和多孔黏弹性地基中所考虑的各无量纲量的影响. 根据不同的边界条件采用正则模态法推导出无量纲竖向位移、超孔隙水压力、竖向应力和温度的解析表达式, 结合算例分析了不同变量对各物理量的影响. 正则模态法是一种加权残差法, 可不经正、反积分变换将方程快速解耦并消除数值反变换的局限性. 结果表明: 无论何种载荷作用时, 载荷频率变化对所有考虑的物理量均有明显的影响; 孔隙率和渗透系数均对无量纲超孔隙水压力有明显的影响, 当仅考虑热载荷作用时, 孔隙率和渗透系数变化对无量纲温度均无影响. 正则模态法可广泛应用于岩土工程领域, 尤其适用于商业建筑、高速铁路和公路能源基础的热、力学特性研究中. 该研究结果可为工程施工奠定一定的理论基础, 具有一定的指导性意义. 

DYNAMIC COUPLED THERMO-HYDRO-MECHANICAL PROBLEM FOR SATURATED POROUS VISCOELASTIC FOUNDATION

Natural soil often has the characteristics of rheology due to different depositional conditions and stress states. The present paper focuses on investigated the effects of different porosity and permeability coefficient in saturated porous foundation which considered the viscoelastic relaxation times with coupled thermo-hydro-mechanical fields under external load. A two-dimensional coupled thermo-hydro-mechanical dynamics problem for a half-space on an isotropic, uniform, fully saturated, and poroviscoelastic soil (THMVD) whose surface is subjected to either mechanical force or thermal load based on the Biot's wave theory of porous media, Darcy's law, and Lord-Shulman (L-S) generalized thermoelastic theory with Kelvin-Voigt viscoelastic model is investigated. The general relationships among the non-dimensional vertical displacement, excess pore water pressure, vertical stress, and temperature distribution are then deduced via normal mode analysis and depicted graphically. Normal mode analysis is a method using weighted residuals to derive analytical solutions. Via this method, the equation can be divided into two parts without integral transformation and inverse transformation, thereby increasing the speed of decoupling and eliminating the limitation of numerical inverse transformation. The effects of the porosity and the permeability coefficient on the four different physical variables have been investigated. It can be shown that: whatever load is being considered, the variation of load frequencies have obvious effect on all the considered physical variables; the porosity and permeability have the most obvious influence on non-dimension excess pore water pressure. When thermal loads were considered only, the variation of porosity and permeability coefficient had barly effect on non-dimension temperature. This proposed derivation method can be widely applied in the geotechnical engineering field, especially with regard to the mechanical and thermal behaviors of commercial buildings, high-speed railways, and highway energy foundations. The research results of this problem can lay a certain theoretical foundation for engineering construction and have a certain guiding significance.