Location: Watershed Physical Processes ResearchTitle: Wind-induced ground motion: Dynamic model and nonuniform structure for ground
|MOHAMMADI, M - University Of Mississippi|
|HICKEY, CRAIG - University Of Mississippi|
|RASPET, RICHARD - University Of Mississippi|
|NADERYAN, VAHID - University Of Mississippi|
Submitted to: Journal of Geophysical Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/17/2019
Publication Date: 7/27/2019
Citation: Mohammadi, M., Hickey, C.J., Raspet, R., Naderyan, V. 2019. Wind-induced ground motion: Dynamic model and nonuniform structure for ground. Journal of Geophysical Research: Solid Earth. 124(8):8478-8490. https://doi.org/10.1029/2019JB017562.
Interpretive Summary: The mechanical behavior of soils plays an important role in a many agricultural processes. Measuring these soil mechanical properties via seismic methods requires a mechanical vibratory source and a sensor to record the resulting ground vibrations. To allow for rapid wide area coverage, progress is being made on non-contact remote vibration measurements using various optical techniques such laser Doppler vibrometer. However, shaking the ground requires a significant amount of energy and using a non-contact source has been limited to acoustic loudspeakers. In this paper, fundamental research using wind induced ground vibrations as a “source of opportunity” for seismic interrogation of near surface soils is presented. This research indicates that the wind-induced source distribution must be improved to predict the observed equivalency of the vertical and horizontal deformations of the soil surface.
Technical Abstract: Wind-induced ground vibrations are a source of noise in seismic surveys. In a previous study, a wind-ground coupling theory was developed to predict the power spectral density of ground motions caused by wind perturbations on the ground surface. The prediction was developed using a superposition of the point source response of an elastic isotropic homogeneous medium deforming quasi-statically with the statistical description of the wind-induced pressure fluctuations on the ground. Model predictions and field measurements were in agreement for the normal component of the displacement but underpredicted the horizontal component. In this paper, two generalizations are investigated to see if they lead to increased horizontal displacement predictions: (1) First, the dynamic point source response is calculated and incorporated into the ground displacement calculation. Measured ground responses are used to incorporate losses into the dynamic calculation. (2) The quasi-static response function for three different types of nonuniform grounds are calculated and used in the seismic wind noise superposition. The dynamic point source response and the three more realistic ground models result in larger horizontal displacements for the point source at distances on the order of 1 m or greater from the source. However, the superposition to predict the seismic wind noise is dominated by the displacements very close to the point source where the prediction is unchanged. This research indicates that the modeling of the wind-induced pressure source distribution must be improved to predict the observed equivalency of the vertical and horizontal displacements.