The Study Of The Influences Of Poro-elastic Ground For Acoustic Waves And Ground Vibration

Blasts, aircraft, and heavy weapons shooting create low frequency impulsivesound waves which propagate over long distances, and can create a majorenvironmental effect for military training fields. Such impulsive sound sources disturbneighbours more through the vibration and rattling induced in building, than by thedirect audible sound itself. The perception of whole body vibration includesfrequencies down to1Hz and the first natural frequencies of the building walls, floorsand roofs are typical in the range1-30Hz, that also correspond with the dominatingfrequencies from airblasts propagating along a few kilometers of distance.Atmosphere topography and ground conditions affect the sound propagationdifferently than at higher frequencies, and general propagating models fail at lowfrequencies. Therefore, in this paper, layered ground model is established based onBiot theory to study the impact on the ground half-space and layered soundabsorption.First of all, in the establishment and analysis of the model, the basic theoryof Biot’s porous media theory(1956) is very important. So this article made a detailedunderstanding of Biot theory, and used the established two-dimensional analysismodel–Multipor model, apply Matlab to proceed numerical calculation of this modeland deduce the expression of layered poro-elastic ground acoustic admittance, it isvery convenient for the analysis and comparison in the below.Secondly, this paper introduces two kinds of rigid frame model: Taraldsen-Darcymodel (2005), and Attenborough four parameters model (1985), the model in thisarticle is compared with them. Through changing the incidence angle, flow resistivityand the frequency to compare three models, it can be found that the results ofMultipor model accord with two models, and is even more important than the twomodels. Multipor model can be used to analyze the layered structure and good resultsare obtained. It is the key to discuss the ground absorption, so in order to more clearlyshow the effect of sound absorption, mapping and analyzing the additional acousticattenuation change rule. Finally, in the porous medium, the porous medium boundary conditions such asopened pores and closed pores on the boundary have a different impact on soundwave propagation, so the discussion of opened and closed pores on the boundary arealso necessary. The opened and closed pore boundaries are used to research the effectson the ground acoustic admittance. Compare and analyze the characteristic of clayand sand. The change of the pore in the poro-elastic media are different, in this article,we also investigate the impact of the pore size distribution on the ground soundabsorption.