Advances in Unsaturated Soil Mechanics

Abstract

Most of soils above the groundwater level encountered in the engineering were in the state of non-stauration. The special soils such as loess, expansive soil and artificial fill were all typical unsaturated soils. Advances in unsaturated soil mechanics were lower than those in saturated soil mechanics. The restricted factors were as follows: 1. Testing technique was relatively not perfect. The test difficulties of unsaturated soil were as follows: (1) It was composed of solid phase, fluid phase, gas phase and contraction membrane. It was very difficult to measure the stress and deformation of the above four phases individually. (2) The suction value ranges from 0 kPa to 106 kPa. But it was very difficult to measure the matrix suction when its value was greater than 80 kPa. (3) As its permeability coefficient was small, the test duration was long. 2. Although it has been presented many constitutive relations such as elastic models, elastic-plastic models, damages models and thermo-mechanical models, the theoretical system of unsaturated soil was far immature. The new constitutive model should describe the reversible and irreversible change process along with the stress and suction change process.