Evaluate Geophysical Methods to Detect Underground Voids

Non-intrusive tests such as ground-penetrating radar (GPR), spectral analysis of surface waves (SASW), multi-channel analysis of surface waves (MASW), and micro-tremor array measurement (MAM) can produce two-or three-dimensional subsurface stiffness profiles from measurements at the ground surface. Electromagnetic tests like GPR and electrical resistivity imaging (ERI) can identify layering, but cannot resolve material stiffness; seismic methods like SASW and MASW can resolve layer thickness and stiffness. Collectively, these methods can fill in the gaps between boreholes much more reliably than interpolation and detect isolated zones of soft or stiff material that could be missed by a borehole investigation. Unfortunately, these methods all struggle to resolve subsurface layering in the presence of certain anomalies. Impedance contrasts, moisture, and cavities can affect different tests in different ways. The same seismic and electromagnetic principles can be used to measure subsurface characteristics from inside of a borehole. The downhole seismic tests measure the subsurface stiffness of conical regions between a borehole and the ground surface. Crosshole seismic tests measure subsurface stiffness along linear paths at multiple depths between boreholes. Borehole GPR tests can produce imaging between two boreholes (GPR tomography), but can also produce omni-directional imaging from a single borehole. Geophysical borehole methods sample more material than the borehole itself, but less material than their ground-surface counterparts. This makes advanced borehole methods ideal for locating anomalies in precisely targeted locations. The research team will address the following: (1.) Review existing literature on this topic and assess the value of research. (2.) Conduct and oversee a battery of ground surface and borehole geophysical surveys, conventional soil borings, and rock corings to detect underground voids at the test locations. TxDOT will provide two or more test locations where the subsurface is karstic and known to include voids. (3.) Examine the recorded data and compare the results with the known ground profile at each test location. (4.) Document all findings and summarize the advantages and limitations of each test method studied.

Language

  • English

Project

  • Status: Active
  • Funding: $328525
  • Contract Numbers:

    0-7071

  • Sponsor Organizations:

    Texas Department of Transportation

    125 E. 11th Street
    Austin, TX  United States  78701-2483
  • Managing Organizations:

    Texas Department of Transportation

    125 E. 11th Street
    Austin, TX  United States  78701-2483
  • Project Managers:

    Steele, Joanne

  • Performing Organizations:

    Center for Transportation Research

    3925 W. Braker Lane
    Austin, TX  United States  78759
  • Principal Investigators:

    Kallivokas, Loukas

  • Start Date: 20200901
  • Expected Completion Date: 20230131
  • Actual Completion Date: 0

Subject/Index Terms

Filing Info

  • Accession Number: 01766429
  • Record Type: Research project
  • Source Agency: Texas Department of Transportation
  • Contract Numbers: 0-7071
  • Files: RIP, STATEDOT
  • Created Date: Mar 3 2021 10:36AM