Masaru ANZAI

Failure Criterion of Unsaturated Soil Considering Tensile Stress

Hirofumi TOYOTA

The failure criterion on unsaturated soils has been proposed by using the results of triaxial tests or box shear tests. However, although there is plenty of unsaturated ground under low confining pressure near the surface of the earth, the application of the failure criterion under low confining pressure has not been confirmed. To give an example concerning ground failure under low confining pressure, there is a possibility that the unsaturated surface of a steep slope may cause destruction owing to stress release induced by cutting or excavation.
Therefore, failure criterion on unsaturated soil under low confining stress conditions was examined by using a hollow cylindrical torsion shear apparatus. Consequently, it was confirmed from the experiment that the failure of unsaturated soil occurred promptly when the net minimum principal stress became negative. Finally, the failure criterion on unsaturated soil under three-dimensional stress conditions considering tensile stress is proposed from the experimental results.