6E-2. The Acoustoelastic Effect of Love Waves in Elastic-Plastic Deformed Layered Rocks

The influences of statically deformed state including both the elastic and plastic deformations induced by applied uniaxial stresses on the Love waves in layered rocks are investigated on the basis of the acoustoelastic theory for elastic-plastic materials. The phase velocity equations of the Love waves are obtained by direct boundary conditions. The acoustoelastic effects of elastic and elastic-plastic deformations in rocks caused by static stresses are discussed by numerical results in detail. Acoustoelastic effects of Love waves exhibit similar trend, acoustoelastic effect increases rapidly with the frequency-thickness product and the velocity change approximates a constant value for thick layer and high frequency limit. Elastic-plastic deformations in the Castlegate layered rock obviously modify the phase velocities of the Love waves and cutoff points for the high-order modes.