Response of two layers overlaying a half-space to a suddenly applied pointforce

Expressions for the elastodynamic displacements, generated by a normal poin t force acting on the top layer of two isotropic layers overlaying an isotr opic half-space, are derived. Generalized ray theory is used to develop the displacement expressions. In particular, a combinatorial technique for cou nting the number of wave rays simultaneously arriving at a specific point o n the free surface of the top layer is developed. Reflection and transmissi on coefficients are derived, the different travel paths are analyzed, the p roducts of the reflection and transmission coefficients are generated, and the arrival times of signals traveling along various rays, including head w aves, are obtained. A computer program has been developed for efficient num erical implementation of the formulation. Numerical results are shown. (C) 2000 Elsevier Science B.V. All rights reserved.