1. Presentation

Soils, like all other materials, deform when a load is applied to them. In accordance with the general principles of soil mechanics, deformations in saturated soils are linked to variations in effective stresses, i.e. variations in the difference between total stresses and pore water pressure. Total stresses are created by gravity forces and other loads applied to the soil surface (by embankments, surface foundations, inverts, etc.) or within the soil mass (deep foundations, tunnels, etc.). Pore pressures can vary independently due to groundwater drawdown or variations in the degree of saturation in unsaturated soils. In dry soils, pore water pressure is zero and deformations are directly linked to variations in applied loads. In the case of unsaturated soils, the evaluation of deformations is more complex (see article Water in unsaturated soils ), but they also result...