The Stokes-Darcy system is recently developing a mathematical theory for the numerical solution of the Stokes and Darcy coupled equations,which frequently appears in the porous media.E.g.,It shows that the singular solution of Biots dynamic equation in 3-D for displacement and stress can be expressed in the form of eikr/r(where r is radial distance,k is wave numbers,i is an imaginary unit)[1,2].The significance of the above results is that the solution based on Stokes-Darcy system is equivalent to the result of functional analysis—it is an extreme value concerning the field equation and its initial conditions,which can be described by the general variational principle of linear elastic dynamics and Hamilton continuum theory,it is as same as the Stokes state in the single media.Thus,it is desirable to seek the fundamental solution of porous dynamics that is expressed in the form eikr/r.With the application of Stokes-Darcy system,the first(Somigliana),second(Volterra)or mixed(Curtin)boundary value problems can been strictly defined in an elastic system through integral equations[3-5].For Stokes-Darcy system utilizing the interchangeable Stokess formula for frequency-time domain,the closed form fundamental solutions in time-domain for Biots porous dynamics equations can be obtained conveniently,so that in accordance with De Hoops suggestion [6](De Hoop,1958)3-D Greens function in U-P formation for porous medium subjected to a concentrated force(which has been derived by the authors in an earlier paper [7,8])can be integrated in order to obtain 2-D forms.The analysis results subjected to a Dirac δ(t)and Heaviside force H(t)can be presented readily.The numerical results of action of Heaviside force can be exploited to compare to Chens results in 1994 [4].It is interest that the results differ in form,but they are identical in numerically.Since the form of solutions is concise in Stokes-Darcy system,a numerical investigation of dynamic response for a tunnel of semicircle section(Fig.1)subjected to a stimulation δ(t)in the half space of the saturated soil is performed in BEM readily.The numerical results are shown in Figs.2-5.It may benefit investigation dynamic issue of a saturated porous medium(Wilmanski,2006)[9].