Laboratory assessment of waves’ velocities and moduli of some rocks

摘要

The waves’ velocities–compression and shear–are used for estimation of deformability characteristicsrn(in dynamic state) in rock engineering. However, there are three serious limitations of the abovernapproach; and these are highlighted using data of three variants of gneiss. One is that, at times, in dry state,rneven negative modulus values are obtained. Second drawback is that, invariably, the computed values of dynamicrnmodulus are higher in saturated state compared to dry state; whereas, the logic suggests, and also thernexperience with, and the presented data of, the static modulus shows that the modulus value reduces on saturation.rnThirdly, for low modulus rocks, on saturation, the percentage increase in dynamic modulus is very high.rnUsing database of 38, including phyllite and variants of schist, conglomerate, gneiss, quartzite, basalt andrnsandstone, the correlation between static modulus of elasticity in saturated state and compression wave velocityrnis established.