Application of ultrasonic technology for physical-mechanical properties of frozen soils

Ultrasonic measurement of dilatational and shear wave velocities for frozen clay, frozen loess and frozen Peking fine sand were carried out on cylindrical specimen under different freezing temperature. Our measurements revealed that the influence of soil grain size and freezing temperature on ultrasonic wave propagating velocities in frozen soils is due to the variation of unfrozen water which was adjusted by the above mentioned factors under the other conditions being equal. The coarser the soil grains, the higher the ultrasonic velocities become. Although almost all specimen velocities increase with decreasing temperature, the rate of increase with reducing temperature is different, which follow in order frozen clay, frozen loess, and frozen sands. We determined the dynamic mechanical parameters by measured ultrasonic wave velocities in tested frozen soils based on the elastic theory and compared the results with the previous results obtained by resonant frequency and cyclic triaxial testing methods. It is proved that the dynamic mechanical parameters could be determined by the acoustic wave methods.