About the sources acting on the free boundary of porous Biot medium and about reflection on this boundary

A homogeneous isotropic porous Biot half-space $z\ge0$ with free boundary $z=0$ is considered. This half-space is excited by the point sources situated on the boundary $z=0$ and applied to the elastic phase. Four sources: 1) Normal force, 2) Center of tangential forces, 3) Center of rotation, and 4) Tangential force are considered. For all sources the wave fields are established. The relation between the wave fields in the porous medium and the corresponding wave fields in the elastic medium is investigated. The reflection coefficients on the free boundary of the porous Biot half-space are defined and studied.