孔隙率各向异性下饱和多孔弹性地基动力响应
DYNAMIC RESPONSE OF SATURATED POROUS ELASTIC FOUNDATION UNDER POROSITY ANISOTROPY
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摘要: 由于不同的沉积条件和应力状态, 天然土体通常表现出一定的各向异性特征. 文章研究地基上表面受温度载荷和机械载荷时, 孔隙率各向异性参数变化对饱和多孔弹性地基热-水-力耦合动力响应问题的影响. 基于Lord-Shulman广义热弹性理论, 结合孔隙率各向异性基本假设, 建立了孔隙率各向异性饱和多孔弹性地基热-水-力耦合动力响应模型, 利用正则模态法推导出无量纲竖向位移、超孔隙水压力、竖向应力和温度分布的解析表达式并加以图示. 正则模态法是一种利用加权残差求得解析解的方法, 相较于其他方法能快速求解偏微分方程. 当孔隙率各向异性参数为1时, 可将该各向异性耦合动力响应模型退化为热-水-力耦合动力响应模型验证该地基模型的合理性. 着重分析了孔隙率各向异性参数变化对不同物理量的影响. 结果表明: 孔隙率各向异性参数变化对物理量均有一定影响. 在地基上表面受温度载荷作用时, 对超孔隙水压力和竖向应力影响最为明显; 在地基上表面受机械载荷作用时, 对超孔隙水压力和温度影响明显. 整体而言, 无论地基上表面受何种载荷, 随着各向异性参数增大, 峰值逐渐减小, 在地基深度增加方向峰值所在位置向靠近地基上表面方向移动.Abstract: Natural soils usually exhibit some anisotropic characteristics due to different deposition conditions and stress states. This study investigated the effects of coupled thermo-hydro-mechanical dynamics on an anisotropy of porosity, fully saturated, and poroelastic half-space subgrade whose surface is subjected to either thermal load or mechanical load in the direction of increasing the depth of the foundation and the direction of the wave propagation. Based on the Lord-Shulman generalized thermoelastic theory and the basic assumption of anisotropy of porosity, the coupled thermo-hydro-mechanical dynamic model for the porosity anisotropy saturated porous elastic foundation is established. The general relationships among non-dimensional vertical displacement, excess pore water pressure, vertical stress, and temperature distribution deduce by using normal mode analysis and depict them graphically. Normal mode analysis is a method using weighted residuals to derive analytical solutions and can thus solve partial differential equations more quickly compared to other methods. When the anisotropic parameter of porosity equals one the dynamic model of this anisotropic foundation can be reduced to a foundation model consistent with the coupled thermo-hydro-mechanical dynamic model, thus verifying the accuracy of the foundation model. The effects of anisotropic parameters of porosity on different physical variables are analyzed emphatically. The results show that the different anisotropic porosity coefficient parameters has a certain influence on all physical variables. The anisotropic porosity has a significant effect on the non-dimensional excess pore water pressure and the vertical stress when the upper surface of the foundation under thermal load, while has obviously effect on the excess pore water and temperature under mechanical load. As a whole, whatever the load is on the surface of the foundation, the peak of the curve decreases gradually and the location of the peak moves closer to the surface in the direction of increasing along the foundation depth as the increase of anisotropy parameters.