Amplification Of Love Waves By Cavities In A Layered Half-Space

According with the appearance of more and more underground buildings, people pay more attention to the seismic response of the site. The analysis of wave propagation in layered soil is important both in theory and engineering. J.P.Wolf derived dynamic-stiffness matrix of elastic layered soil, as well as green's functions for distributed loads acting on inclined line in a layered site, which formed a complete theory for wave propagation in layered site and dynamic soil-structure interaction. How to extend Wolf's theory to the case of Love waves will be mainly resolved in this paper.Amplification of Love waves by a cavity in a layered half-space is analyzed by indirect boundary element method in frequency domain. The free-field response was calculated to determine the stress on the line which will form the surface of the cavity. Then fictitious distributed loads are applied on the same line in the free field to calculate Green's functions for the displacements and stress, and the displacements response arising from the waves in the free-field and from the fictitious distributed loads are summed up to obtain the solution.Free-filed response of layered site is systematically researched by direct stiffness method. The dispersion and damping identity of Love-waves and the amplification of SH waves and Love waves are given in this paper. A homogeneous layer resting on a half-space and multi-layers resting on a half-space are calculated.The differences of amplification of elastic waves by a cavity or two in homogeneous half-space and multi-layers resting on a half-space are studied by using the indirect boundary-element method. The necessity and rationality of using layered model are pointed. This method can be used in the dynamic analysis of underground structure such as cavity.