The problem of a half-space with cavity under vertically incident waves was solved by many researchers using different approaches. However, substantially different solutions were obtained, partially due to the difference in the method of formulation, and partially due to the lack of complete identical data for use in analysis. In this paper, the finite/infinite element approach has been adopted to study the two-dimensional response of an elastic half-space containing a buried, unlined, infinitely long cylindrical of circular shape subjected to harmonic P and SV waves. First, the analysis procedure based on the finite and infinite elements is summarized. Second, considerations in preparing the finite element mesh to ensure the accuracy and convergence of the solution are presented. Next, the validity of the procedure of solution is verified for some intuitive, fundamental cases. Finally, the problems solved by previous researchers with identical or assumed data will be re-solved, along with discussions on the discrepancies existing among the three solutions. One feature with the finite/infinite element approach is that it is simple and straightforward, involving less assumptions and mathematical operations, whose reliability has been verified in solving various soil vibration problems. The fact that the present solutions are in close agreement to those by Luco and De Barros (1994) for all the cases studied indicates that the latter is the most reliable one among the existing theories.
