ABSTRACT

Experimental studies, such as performing triaxial compression tests while controlling the matric suction using axis translation technique, are useful in establishing the mathematical modeling of unsaturated soils. In many relevant studies, the triaxial tests are processed under drained and exhausted condition, in which the matric suction is kept constant during shearing stage. Since few experimental studies have been conducted under undrained and unexhausted condition, shear properties of unsaturated soil under different drainage and exhaust conditions are investigated in this study. In this test program, the triaxial compression tests are conducted on a compacted unsaturated soil, where an initial matric suction of 20 kPa was applied to soil specimens using the pressure membrane technique instead of a ceramic disk. Change in the matric suction is observed as results of measurement of both the pore-air pressure and the pore-water pressure. Effective degree of saturation was employed in evaluating the effective stresses in unsaturated soil instead of χ in Bishop’s equation.