%0 Journal Article
%A Entwisle, D. C.
%A McCann, D. M.
%T An assessment of the use of Christensen’s equation for the prediction of shear wave velocity and engineering parameters
%D 1990
%R 10.1144/GSL.SP.1990.048.01.29
%J Geological Society, London, Special Publications
%P 347-354
%V 48
%N 1
%X The full wave train sonic log is widely used in civil engineering for the determination of formation dynamic elastic moduli. In some instances, the shear wave amplitude is too small to time its arrival accurately. In these situations Christensen’s equation can be used to predict the shear wave velocity from the compressional wave velocity and the formation density. In this paper the origins of Christensen’s equation are investigated in relation to both field and laboratory studies on a wide range of natural materials. It is suggested that differences between the measured and predicted shear wave velocities are lithologically based. The equation is not valid for uncemented sediments. The dynamic elastic moduli reflect these differences. Bulk modulus is least affected by large differences in shear wave velocity. There is no relationship between the predicted and the measured values for Poisson’s ratio. The use of Christensen’s equation will be improved if corrections are made locally for lithology.
%U https://sp.lyellcollection.org/content/specpubgsl/48/1/347.full.pdf