Investigating the Influence of Principal Stress Directions and Intermediate Principal Stress on the Shear Strength ofUnsaturated Silty Soil Using the Hollow Cylinder Apparatus

In this paper, ۱۲ series of tests using the hollow cylinder apparatus are conducted to investigate the coupledeffects of α and b parameters on studying the induced anisotropy effects in fine-grained unsaturated soils.The selected soil is a mixture of Firouzkouh silty soil and bentonite, which is prepared using the moisttamping method at optimal moisture content and reaches a degree of saturation of ۳۰% during the dryingpath. The experiments are carried out under controlled moisture conditions. It is observed that an increasein the α angle results in a decrease in the shear modulus and soil strength, as well as an increase in malleablebehavior.

Keywords:

Induced anisotropy , unsaturated soil , hollow cylinder apparatus , fine-grained soilconstitutive model