Strength and Stiffness Properties of an Unsaturated Clayey Silt: Experimental Study at High Degrees of Saturation

Abstract

Unsaturated constant water content triaxial compression tests with suction measurement, using an Imperial College tensiometer, and saturated consolidated undrained tests were conducted on reconstituted brickearth, a naturally unsaturated clayey silt from London. The results show that the saturated effective stress can be applied to the critical state line (CSL) and normalized stiffness for unsaturated brickearth but that Bishop's effective stress variable gives a slightly improved CSL. The stiffness derived from local instrumentation demonstrates that Bishop's effective stress is also beneficial for normalizing the stiffness modulus over the small-strain range (up to axial strains of about 3%).