基于Biot理论的饱和砂质沉积物声传播模型及耗散机制分析
Analysis of acoustic propagation models and dissipation mechanisms of saturated sandy sediments based on the Biot theory
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摘要: 为研究海底浅表砂质沉积物的频散特性, 利用由多孔介质理论发展而来的Biot模型、Biot-Stoll模型和附加接触喷流与剪切拖曳的Biot-Stoll模型(BICSQS模型), 对比三种声传播模型描述下的典型砂质沉积物中纵波和横波频散特性, 分析了模型中不同耗散机制对其声频散关系的影响; 结合实测数据探讨了各模型对砂质沉积物的适用性。结果表明, 沉积物的声频散特性是不同耗散机制共同作用的结果, 不同频段内的主要耗散机制不同, 相同频段内耗散机制对纵波和横波的传播影响亦不同; 随着频率的增加, 相比Biot和Biot-Stoll模型的预测结果, 砂质沉积物的实测声速和衰减系数表现出更高的频散趋势, 而BICSQS模型可更合理地预测和解释试验现象, 适用性更好。Abstract: 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.