Analysis of acoustic propagation models and dissipation mechanisms of saturated sandy sediments based on the Biot theory

To investigate the dispersion characteristics of shallow sandy sediments on the seabed,a comparative analysis was conducted on the longitudinal and transverse wave dispersion features in typical sandy sediments described by the three acoustic propagation models using the Biot model,the Biot-Stoll model and the Biot-Stoll with contact squirt flow and shear drag(BICSQS)model developed from the theory of porous media.The effects of different dissipation mechanisms in the models on the acoustic dispersion relationship were revealed.Furthermore,the applicability of the models to sandy sediments was explored using integrating empirical data.The results indicate that the acoustic dispersion characteristics of sediments are the result of different dissipation mechanisms,which are different in different frequency bands and have different effects on the propagation of longitudinal and transverse waves in the same frequency band.As the frequency increases,the measured acoustic speed and attenuation of sandy sediments exhibit higher dispersion trends than those predicted by the Biot and Biot-Stoll models.In contrast,the BICSQS model demonstrates a more reasonable prediction and interpretation of experimental phenomena with better applicability.