Reconciling soil-water retention properties and shear strength parameters of compacted clayey soils via suction-controlled ring shear testing

Abstract

A preliminary experimental program has been undertaken to assess suction-controlled peak and residual shear strength properties of a statically compacted, moderate plasticity clayey soil. The experimental program was accomplished in a fully servo/suction-controlled ring shear apparatus, suitable for testing unsaturated soils under large deformations via the axis-translation technique. The test results highlight the important role played by matric suction on residual shear strength behaviour of compacted clayey soils. For the range of net normal stresses and suction states investigated, the increase in peak shear strength with increasing suction was found to be significantly nonlinear for the clayey soil. A distinct correspondence was also observed between the nonlinear nature of peak shear strength envelope, with respect to increasing matric suction, and the soil-water retention curve. The residual failure envelope, however, remains reasonably linear for the range of suction values induced in the present work via axis-translation.