Uniaxial compressive strength of frozen silt under constant deformation rates

Abstract

Uniaxial compressive strength tests were conducted on remolded, saturated Fairbanks frozen silt under various constant machine speeds, temperatures and dry densities. Test results show that the peak strength σ m of frozen silt is not sensitive to dry density (or water content) at −2°C, especially at relatively high strain rates, but is very sensitive to temperature and applied strain rate. However, the failure strain (strain at σ m ) is not sensitive to temperature and strain rate within a wide range of strain rate, but is very sensitive to dry density. It has been found that the initial yield strength σ y consistently increases with decreasing dry unit weight. The initial yield strain (strain at σ y ) is almost independent of dry density and temperature, but varies with strain rate. Its magnitude ranges from 0.2 to 0.6% as strain rate varies from 1.1 × 10 −6 to 5.7 × 10 −3 s −1, which is very close to the strain at yield for fine-grained polycrystalline ice (Hawkes and Mellor, 1972; Mellor and Cole, 1982). The initial tangent modulus of frozen silt is found to be nearly independent of strain rate, but the 50% strength modulus is closely related to strain rate. The test results indicate that there is a definite relationship between the two moduli.