1. The response of soils to dynamic loadings. Report No. 24: Wave velocities through partially saturated sand-clay mixtures: H.A. Balakrishna Rao. Massachussetts Inst. of Tech., Cambridge. Dept. of Civil Engineering

Abstract

Abstract : Investigations concerning the velocity of dilatational and shear waves through compacted specimens of kaolinite and kaolinite-sand mixtures at different moisture contents have been described. The delay time between the input and output signals from piezoelectric crystals located at the two ends of compacted samples has been utilized to evaluate the wave velocity. The results reveal that there are two important parameters involved in the propagation of dilatational waves: confining stress and moisture content. An increase in confining stress tends to increase the dilatational wave velocities. An increase in the moisture content also tends to increase the dilatational wave velocity, particularly at high saturation. The magnitude of wave velocity measured in various mixtures is similar to those in dense sand. The results of shear wave tests show a reduction of shear wave velocity with increase in moisture content. The decrease is attributed partly to the decrease in the rigidity of the fabric and partly to addition of mass which contributes to the inertia force. For a constant dry density, the presence of sand tends to decrease the wave velocity, apparently because differing amounts of sand required different compactive efforts. (Author)