Interpretation of the Bearing Capacity of Unsaturated Fine-Grained Soil Using the Modified Effective and the Modified Total Stress Approaches

Abstract

The bearing capacity of unsaturated soils is commonly estimated using the conventional shear-strength parameters determined from drained loading conditions regardless of soil type and drainage condition. However, the use of drained shear-strength parameters to interpret the bearing capacity of unsaturated fine-grained soils is not reliable because there are uncertainties with respect to the drainage conditions of both the pore-air and pore-water pressures. In the current study, a series of model footing tests is conducted in statically compacted unsaturated fine-grained soils. The model footing test results are interpreted using the modified effective-stress and total stress approaches considering the influence of matric suction. In addition, the validity of the modified total stress approach is tested using in situ plate-load test results in unsaturated fine-grained soils. The advantages, disadvantages, and limitations of using the modified effective-stress and modified total-stress approaches for engineering practice applications are discussed in this paper.