Comments on ‘‘Reflection of elastic waves under initial stress at a free surface: <i>P</i> and <i>S</i> <i>V</i> motion’’ [J. Acoust. Soc. Am. <b>7</b> <b>2</b>, 255–263 (1982)]

Abstract

In the paper under discussion, Chattopadhyay et al. [J. Acoust. Soc. Am. 72, 255–263 (1982)] studied the problem of the reflection of elastic waves at the plane free boundary of an initially stressed sandy medium. The authors effected the decoupling of the P and SV motion for waves propagating in the horizontal and vertical directions which are the principal directions of the initial stress tensor considered. However, while discussing the reflection of P and SV waves, the authors use the above decoupling for waves propagating in an arbitrary direction. In fact, the expressions for the displacement potentials assumed by the authors do not satisfy the equations of motion. Consequently, most of the equations and results of the subject paper are either irrelevant or incorrect. Similarly, the results obtained by the authors for Rayleigh waves in an initially stressed sandy medium are also wrong.