HR: 12:10h
AN: NS32A-06    [Abstracts]
TI: Seismic Waveform Parameters and the Engineering Properties of Unconsolidated Sediments: Laboratory Measurements and Models
AU: * Boadu, F
EM: boadu@duke.edu
AF: Dept. Of Civil and Environmental Engineering, Duke University, Durham, NC 27708, United States
AU: Owusu-Nimo, F
EM: frederick.owusunimo@duke.edu
AF: Dept. Of Civil and Environmental Engineering, Duke University, Durham, NC 27708, United States
AB: The ability to locate and monitor weaker soil/rock units in the subsurface non-invasively using geophysical measurements would be very useful for geotechnical engineers involved in geo-hazard mitigation. Velocity and attenuation studies indicate that velocity and attenuation of transmitted P-waves are affected by the microstructure and mechanical state of the sediments. This investigative work explores the use of direct information from the spectra of waveforms propagating though the unconsolidated medium, hypothesized here to provide us with useful information about the engineering and petrophysical properties of the medium. Numerical investigations using a reformulation of Biot's theory by indicate that the spectral signature, shape and frequency content as well as the distribution of spectral energy are sensitive to the porosity, degree of saturation and the skeletal frame modulus of the medium, which are important in determining its mechanical stability. It will be shown from laboratory investigations that the spectral signature, spectral energy distribution and frequency content of seismic waveforms propagating through unconsolidated geomaterials provide valuable information that can be used to characterize their engineering and petrophysical properties. Such investigations are desirable and will be of great interest to geotechnical engineers involved in monitoring and assessment of the strength and stability conditions of subsurface geo-materials and a geo-hazard mitigation and assessment.
DE: 5102 Acoustic properties
DE: 5144 Wave attenuation
SC: Near-Surface Geophysics [NS]
MN: 2009 Joint Assembly