Principle of Effective Stress is an Approximated Method

Abstract

Soil mechanics is a powerful theoretical analysis tool in geotechnical engineering. The principle of effective stress is a basis of classic soil mechanics. However, it in fact is an approximated method. This is attributed to three factors. Firstly, the effective stress is an equilibrium equation rather than an independent state variable. Secondly, the effective stress is a variable controlled the deformation behavior and the shear strength of soil, but not the only one. Thirdly, the principle of effective stress is an equivalent method, but not an accurate one. The above viewpoints are justified in this paper as follows. Firstly, it is demonstrated that the soil is a variable and sensitive material. Thus, it is difficult to quantitatively describe soil behaviors by only one variable. Secondly, the definition and the comprehension of the effective stress are discussed. Finally, to deal with complex problems most frequently encountered in geotechnical engineering, two approaches are advised, i.e., choosing additional variables except for the effective stress and using the multi-factor theory.