抄録
The purpose of this paper is to investigate the semi-infinite elastic medium subjected to a vertical harmonic point force in its interior. It may be called dynamic Mindlin problem (I). In the method to analyze it, the basic solutions which have been derived and studied in our previous paper (part I) are used. They are fundamental solutions and potentials for a three dimensional homogeneous, isotropic, elastic medium. In order to examine the resulting solution, next two discussions are done. One is that the solution coincides with dynamic Boussinesq solution when a point force moves from the interior position of the medium to the origin on the free surface of it. The other that is the solution coincides with static Mindlin solution, being wellknown, in the limit when the circular frequency ω, involving in the solution, approaches zero. Displacement curves of U_z and changes of its phases for two cases such as the positions of a point force, 0.6 and 2.0, can be given by integrating the solution numerically, and they are drawn in Fig.1, Fig.2, Fig.3 and Fig.4. The results observed from these figures are discussed. The resulting solution is expressed as the sum of terms of potentials and fundamental solutions. Comparing the value of fundamental solutions with that of potentials, the former are very greater than the latter. It may be concluded from some considerations based on the comparison that the fundamental solutions represent the resulting solution approximately under a certain condition.
