MULTIPLE-SCATTERING OF SH-WAVES BY IMPERFECTLY BONDED INTERFACES WITHINHOMOGENEOUS STRENGTHS

We have developed a new, simple method to calculate elastic waves scat tered by zonally distributed cracks, taking account of multiple crack interactions. In this paper, our method is applied to SH-wave propagat ion in 2-D elastic media. An array of cracks is represented by an impe rfectly bonded interface with a spatially inhomogeneous strength. A se ction of the interface with vanishing strength represents a stress-fre e crack, while a section with a significantly high elastic stiffness a pproximates an intact section. A cracked zone is therefore represented by a multilayered zone, partitioned by many such interfaces. In this formation, the interactions among all cracks can be considered implici tly and a mixed boundary-value problem can be circumvented. In our met hod, the elastic waves scattered by an interface are expanded into dis crete reflected and transmitted plane-wave components. The wavefield i n a cracked zone can be easily calculated by the wave propagator metho d or by the reflection and transmission operator method, on the basis of this expansion. The accuracy of our method is shown to be quite sat isfactory for some examples. The zeroth-order reflection coefficient, which is defined as the coefficient for a reflected-wave component tha t has a reflection angle equal to the incidence angle, is specifically studied for some crack arrays, as an example of the application of ou r method of analysis.