Characteristics of elastic waves in sand–silt mixtures due to freezing

Abstract

The objective of this paper is to characterize the properties of the compressional and shear waves resulting from the freezing of soil. After the sand–silt mixtures with different degrees of saturation (5%, 10%, 20%, 40% and 100%) are prepared in nylon freezing cells, the temperature of the specimens decreased from 20°C to −10°C. During the freezing of the soil, three pairs of piezo disk elements and bender elements, installed at three different locations along the depth, are used for the continuous measurement of the compressional and shear waves. The three properties of elastic waves, represented by velocities, resonant frequencies and amplitudes, are monitored continuously. Significant increases are observed in both of the elastic waves near the temperature of 0°C. As the specimens freeze, the influent factor of the compressional wave velocity changes from the degree of saturation to the ice bonding. After soil freezing, the critical factor that affects the shear wave velocity turns from the confining stress into ice bonding and contact size. The variation of the resonant frequency of the elastic waves according to the temperature and degree of saturation is similar to the variation of the velocity of elastic waves. After soils are frozen, the Poisson's ratio decreases with an increase in the degree of saturation with ice. This study provides fundamental information about the change of properties of elastic waves in soils due to freezing.