Publication
Very-small to large strain dynamic behaviour of unsaturated sand in a wide range of suction
Publisher:
EDP Sciences
Date:
2020
DOI:
10.1051/E3SCONF/202019503002
Abstract: Shear modulus ( G max at very small strain and G at large strain) and constraint modulus at very small strain ( M ) are important soil parameters for static and dynamic analysis in geotechnical applications. However, these dynamic properties of unsaturated soil are rarely reported. In this study, a cyclic simple shear apparatus was newly-modified for allowing both the shear and constrained moduli at both very small and large strains to be measured. Benders or ultrasonic sensors were embedded in an unsaturated soil s le for transmitting/receiving shear- and pressure-wave, respectively. Two very-small-strain tests were conducted to determine the G max , M and soil d ing ratio of a sand for a wide range of suction covering from the boundary-effect, transition and residual zone of the water retention curve of the sand. In addition, six large-strain cyclic simple shear tests were carried out to investigate G . The test results showed that G max and M were approximately constant before reaching the air-entry value, but there was a significant increase in G max as the sand dried further. Yet, M dropped within the transition zone, and interestingly when the suction was beyond the residual value, M increased. M along the wetting path was higher than that along the drying path. The d ing ratio, on the other hand, first reduced before reaching the air-entry value, but it increased at the transition zone and then decreased within the residual zone. At large strain, G / G max also increased as suction increased until reaching the residual zone, beyond which the normalised value show substantial decreased.