非饱和土有效应力公式验证

非饱和土有效应力原理对于非饱和土力学具有奠基性的意义。虽然现有的非饱和土有效应力公式种类很多,但是同时具有一定理论基础和明确物理意义的非饱和土力有效应力公式并不多,而且其适用性有待进一步的验证。为此,笔者首先简要概述了非饱和土有效应力公式的演化历程,并对几种典型的非饱和土有效应力公式的理论依据及物理意义进行了讨论,通过比较发现,邵龙潭采用连续介质力学理论推导得到的饱和与非饱和土统一的有效应力公式与1996年Vanapalli所提出的半经验公式在形式上相似,但是前者却阐明了非饱和土有效应力的物理意义即不包含孔隙流体压强作用的土骨架应力。将该公式与四参数Van Genuchten模型进行结合分别对膨胀土、粉质粘土、粘质砂土以及灰质粘土4种不同种类的非饱和土的抗剪强度进行了预测。结果表明,在试验精度范围内,理论预测值与试验值吻合较好,从而验证了该公式在试验和工程中具有良好的适用性。

The Validation of the Effective Stress Principle of Unsaturated Soils

The effective stress principle of unsaturated soil is significant to the development of unsaturated soil mechanics. Although there are many kinds of the existing formula of effective stress for unsaturated soil, it is difficult to find the formula which combine some theoretical basis and clear physical meaning, what's more, it is necessary to further verify its application. For the purpose, the evolution of the effective stress principle of unsaturated soils were summarized briefly in the first and then the theoretical basis and physical significance of several typical formulas about the effective stress principle of the unsaturated soils were discussed. By comparison, it is found that the effective stress formula derived from the theory of continuum mechanics by Shao L T was similar in form to the semi-empirical formula proposed by Vanapalli in 1996, but the formula raised by Shao revealed that the effective stress was the skeleton stress due to all the external forces excluding pore water pressure. Finally, the formula was aligned with the four parameters Van Genuchten model to predict the strength of expansive soil, silty clay, clay sand and adobe soil. The result indicates that there is a well agreement between the theoretical value and test result within the scope of the test accuracy. Thus it validates the feasibility of the formula used in the tests and projects.