Characterization of compacted silty sand via relative humidity-controlled triaxial testing

¹ Faculty Research Associate, University of Texas at Arlington, Arlington, Texas, 76019, USA.
² Professor, University of Texas at Arlington, Arlington, Texas, 76019, USA.

^a Corresponding author: ujwalkumar.patil@mavs.uta.edu

Abstract

Rather limited experimental evidence is available of triaxial shear-induced response of unsaturated soils at suction states far beyond residual suction. In this work, a fully automated, relative-humidity (Auto-RH) control unit is adapted to a newly implemented double-walled triaxial cell to test compacted silty sand specimens under consider-ably high total suction states via the vapor-pressure technique. The work is intended to gain critical insight into some of the most essential hydro-mechanical features of densely compacted intermediate geomaterials, such as post-peak softening and strain-induced dilatancy, under suction-controlled monotonic shearing. In general, peak strength is followed by large strain-induced softening until critical state is apparently reached. Strain-softening is observed to be-come considerably more pronounced with increasing total suction. The slope of critical state lines, however, remains virtually constant, regardless of induced total suction, in agreement with critical state-based constitutive frameworks previously postulated for unsaturated soils.