The near surface is characterized by using different numerical techniques, among them seismic techniques that are non-destructive. More particularly, for a better understanding of acoustic and seismic measurements in unconsolidated granular media that can constitute the near surface, many studies have been conducted in situ and also at the laboratory scale where theoretical models have been developed. In this article, we want to model such granular media that are difficult to characterize. At the laboratory scale, dry granular media can be modelled with a homogenized power-law elastic model that depends on depth. In this context, we validate numerically a similar power-law elastic model for such media by applying it to a homogenized elastic medium or to the solid frame of a poroelastic medium that consists of solid and air components. By comparing the response of both rheologies, we want to highlight what poroelastic media can bring to better reproduce the experimental data in the time and frequency domains. To achieve this objective, we revisit studies carried out on unconsolidated granular media at the laboratory scale and we compare different models with different rheologies (elastic or poroelastic), dimensions (2D or 3D), boundary conditions (perfectly matched layer/PML, or Dirichlet) and locations of the source (modelled as a vibratory stick or a point force) in order to reproduce the experimental data. We show here that a poroelastic model describes better the amplitudes of the seismograms. Furthermore, we study the sensitivity of the seismic data to the source location, which is crucial to improve the amplitude of the signals and the detection of the different seismic modes.

近地表的特征是使用不同的数值技术，其中包括非破坏性的地震技术。更具体地，为了更好地理解可以构成近地表的松散粒状介质中的声学和地震测量，已经在现场以及在实验室规模上进行了许多研究，其中已经开发了理论模型。在本文中，我们想要对这种难以表征的颗粒介质进行建模。在实验室规模上，可以使用取决于深度的均质幂律弹性模型对干燥颗粒介质进行建模。在这种情况下，我们通过将其应用于均质弹性介质或由固体和空气成分组成的多孔弹性介质的固体框架，在数值上验证了此类介质的类似幂律弹性模型。通过比较两种流变学的响应，我们想要强调多孔弹性介质可以带来什么，以更好地再现时域和频域的实验数据。为了实现这一目标，我们重新审视在实验室规模上对松散颗粒介质进行的研究，并比较具有不同流变性（弹性或多孔弹性）、尺寸（2D 或 3D）、边界条件（完美匹配层/PML 或狄利克雷）的不同模型）和源的位置（建模为振动棒或点力），以便重现实验数据。我们在这里表明，多孔弹性模型可以更好地描述地震图的振幅。此外，我们研究了地震数据对震源位置的敏感性，这对于提高信号幅度和不同地震模式的检测至关重要。