Seismic Imaging to Characterize Subsurface Ground Conditions in Civil Construction

Variable subsurface ground conditions present serious challenges to the civil engineering industry to design, construct, and maintain infrastructure. Accurate knowledge of ground conditions reduces project risk, improves construction performance, prolongs structure life, and prevents waste in over-design. NSA has developed systems that process collected seismic data using tomography and holography techniques to produce detailed, three-dimensional representations of subsurface conditions. Seismic signal waveforms traveling through a complex medium consist of various arrivals from refractions, reflections, scattering, and dispersion. Tomography and holography are proven inversion technologies for estimating location and extent of material property variations causing changes in signal waveforms. This paper will present three case studies describing the types of geotechnical investigations performed by NSA.