有效应力原理解析

Analytical solutions to principle of effective stress

分析了关于饱和土有效应力原理的一些错误理解,基于土颗粒-水相互作用分析,给出了土体中有效应力的物理含义,是单位截面的土体中土颗粒骨架所传递的有效荷载,其大小等于总应力与孔隙水压力之差。利用土体的力平衡方程,一方面证明了Terzaghi饱和土有效应力原理,并分析了该原理的适用范围;另一方面证明了Bishop非饱和土有效应力原理,解释了参量χ的物理含义,将二原理统一在一个力学框架下,从理论上说明了Terzaghi有效应力原理是Bishop有效应力原理在有效饱和度χ=1时的特例,并分析了Bishop非饱和土有效应力原理的适用范围。研究表明,从荷载条件和土性条件两个角度分析有效应力原理,清晰地解释了有效应力的物理概念,并且提出孔隙水压力影响土体力学特性的机理。

By analyzing some misunderstandings about the principle of effective stress for saturated soil,the physical meaning of effective stress of soil is given interaction between soil based on the particle and water.The effective stress of soil is the effective load transferred between the soil particle skeletons in a unit section and equal to the total stress minus the pore water pressure.By using the mechanics balance equation of soil,on the one hand,the Terzaghi principle of effective stress for saturated soil is proved and its sphere of application is analyzed,on the other hand,the Bishop principle of effective stress for unsaturated soil is proved and the physical meaning of parameter χ is explained.By combining the two principles in the same mechanics frame,it is illustrated that the Terzaghi principle of effective stress for saturated soil is one special case of Bishop principle of effective stress when the saturation level χ =1 in theory,and the sphere of application of the Bishop principle of effective stress for unsaturated soil is also analyzed.The researches show that by analyzing the principle of effective stress from two aspects of loading and soil properties,the physical meaning of effective stress is explained clearly,and the mechanism of the influence of pore water pressure mechanics characters of soil is also proposed.