散砂及表层海洋(砂质)沉积物中的声速

根据作者的颗粒介质中的声传播理论,应用熄灭定理,给出了颗粒介质中的声速公式。对表层海洋(砂质)沉积物及气砂中的声速作了数值计算,结果表明,在大气压力下,气砂中的声速比空气中的声速小。而在表层海洋沉积物中,散射相互作用的影响不可忽视,粘滞波相互作用对声速的影响不大。刚性粒子理论结果与发表的实验数据比较符合,弹性粒子理论模型应该说是符合实际的,但给出的结果反而比实验数据小,这表明更多的实验测量是需要的。还比对分析了已发表的实验数据,结果表明,颗粒介质理论是更适宜于研究气砂中的声传播问题。

Sound speed in air-filled sands and marine shallow-layer sediments(sands)

Based on the author's theory for acoustic propagation in granular media and employing the extinction theorem, the sound speed formulae in these media are given. The numerical computations for sound speed in marine sediments and air-filled sands are carried out, the results of which demonstrate that under the normal atmosphere the sound speed in air-filled sands is lower than the sound speed in the air, The numerical results also demonstrate that the influence of scattering interaction between the grains upon the sound speed in the marine shallow-layer sediments (sands) has to be taken into account; however, the interaction of viscous waves can be neglected. The theoretical results obtained from the rigid-granular model seem to match the measured data better than from the elastic-granular model, even the latter model is fitter for the real situation, which means that still more further measurements will be necessary in order to gain an insight into this problem. Through an analysis of experimental data published in journals a conclusion can be drawn that the theory of granular media is suited better than the theory of porous media to deal with the problems of the sound propagation in air-filled sands.