详情

Evaluate Geophysical Methods to Detect Underground Voids

项目名称：	Evaluate Geophysical Methods to Detect Underground Voids
摘要：	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.
状态：	Active
资金：	328525
资助组织：	Texas Department of Transportation
项目负责人：	Steele PMP, CTCM, Joanne
执行机构：	Center for Transportation Research
开始时间：	20200901
预计完成日期：	20230131
主题领域：	Geotechnology