A natural compression law for soils (an advance on e–log p′)

The shortcomings of the curves normally used to describe the change of volume of a soil skeleton with variations in mean effective stress are discussed. The author proposes an alternative approach, without the use of void ratio, adopting specific volume. Expressions are derived to show that natural volumetric stresses and strains are linearly related. Some consequences of this new relationship are examined. The coefficient of volume compressibility is defined, and the theory of soil consolidation in an oedometer investigated. Predictions of pore water pressure and effective stress changes are better than those of the conventional linear theory. The cam clay soil model is modified to give a revised critical state line which is well supported by experimental evidence. Equations are derived which could provide a basis for a simplified presentation of state boundary surfaces. (TRRL)