EXPERIMENTAL STUDY ON STATE BOUNDARY SURFACE OF COMPACTED SILTY SOIL

Abstract

To understand the behavior of unsaturated soil, considerable research has already been done. However, there is limited research to model the behavior of unsaturated soil in a generalized state boundary surface (SBS). SBS is the surface outside which a soil stress state can never exist. It is an envelope surface of all the possible soil stress paths in the p’-q-e space. To investigate the SBS of unsaturated soils, a series of triaxial compression tests were performed in this study under constant water content conditions using a double-cell triaxial test apparatus. The samples were prepared with 80%, 83%, and 86% degrees of compaction and water contents of 20% (Optimum water content) and 25%. All the soil specimens were consolidated isotropically under 500kPa confining pressure before being sheared with a constant void ratio under monotonic loading. The results show that constant void ratio tests depict contour-like lines, which can help in defining the SBS of unsaturated soil.