Ultrasonic Shear Wave Velocities in Sand and Clay

Abstract

Abstract : A study in which the ultrasonic shear wave velocity was measured in sand and clay is described. The use of the shear wave, rather than the longitudinal wave, offers the possibility of studying stress wave propagation through the skeleton of a soil independently of the pore fluid. The apparatus developed used ferreoelectric ceramics to produce and receive a pulsed, torsional shear wave in cylindrical soil samples subjected to various states of hydrostatic stresses. Three soil materials were tested: a coarse, rounded sand, and two types of saturated clay. From the tests on sand it was found that the void ratio and level of effective hydrostatic stress determined the velocity of the shear wave; whereas, the level of shear stress and degree of saturation were found to have only a minor influence. From the tests involving clay samples, it was found that the effective hydrostatic stress and the void ratio most heavily influenced the shear wave velocity, and the three quantities could be interrelated such that specifying any two would determine the third. Measurements taken during secondary consolidation indicate that the shear wave velocity is sensitive to small structural changes occurring during that period. (Author)