渗透力概念的力学分析及广义化探讨

Mechanical fundamentals of seepage force concept and its generalization

渗透力是土力学中重要而艰深的概念之一。在分析渗透力现有成果基础上,首先辨析提出了相关的水力梯度定义和Darcy定律表述之间的协调性问题,从而明确了传统渗透力表述式中水力梯度的协调性定义方法;然后,基于力学机理较严谨的Biot固结理论并引入体力、广义有效应力原理和总渗流势方程等,分析提出适用于广义多孔介质(含土体)的广义渗透力的一种定义,即广义渗透力在力学上是广义有效应力系数张量与总渗流势梯度的点积,这区别于传统假说。在Terzaghi有效应力方程适用的范围内,广义渗透力可以退化为总渗流势梯度这一常见形式。还探讨了渗透力的其他力学性质,以及考虑渗流速度影响的广义渗透力改进途径。所得结论有助于拓展对渗透力概念的认识。

The seepage force is still one of the most fundamental and controversial concepts in soil mechanics.Based on the literature review,the compatibility between the definition of hydraulic gradient and the mathematical description of Darcy＇s law is discussed first,followed by proposing a compatible form of hydraulic gradient definition in the conventional expression for seepage force.By integrating the body force,the general effective stress principle and the total seepage potential equation into the Biot＇s consolidation theory,a strict definition of the general seepage force is obtained for various porous media including soils.The general seepage force proposed herein is the dot product of the general effective stress tensor and the total seepage potential gradient,which differs from conventional explanations of seepage force mechanism.Within the scope of Terzaghi＇s effective stress principle,the general seepage force is reduced to the form of total seepage potential gradient.Other related mechanical properties of seepage force are investigated as well as a further modified formulation for the general seepage force containing seepage velocity.The conclusions may afford profound insight into the concept of seepage force in geotechnical practice.