This research used geophysical methods to detect the presence of sub-vertical failure planes, their direction(s), and their frequency in bedrock beneath soil or glacial drift overburden. Azimuthal measurements using the seismic, electrical resistivity (ER), and electromagnetic conductivity were made to evaluate which techniques might provide the best indication of the bedrock joints, faults, or shear zones. Measurements were made at multiple sites near each of three locations: Jackson, Alpena, and Grand Ledge, Michigan. The first two are former limestone quarries and the third is underlain by sandstone. Seismic measurements began with one or two linear refraction spreads, used to establish thickness of overburden and identify the S waves. The Circular Array Seismic Survey (CASS) was done by placing the 24 geophones around a 10 or 15m radius circle (15 degree intervals), with the shot point in the center, measuring arrival times of the P and S waves. The EM-31 conductivity was used to quickly determine that there were no wires or pipes in or near the survey circle, as well as to profile along the diameters of the circle at 12 different azimuths. Electrical resistivity measurements included linear and azimuthal square arrays. The linear array consisted of expanding 4-electrodes in the fashion used in Schlumberger array, which constitutes a Vertical Electrical Sounding (VES) to determine the resistivity layering and, similar to the linear array in the seismic refraction method, gave a second or independent measure of the depth to bedrock, water table, or other discontinuity when interpreted. The azimuthal square array was used for the resistivity measurements in the same circle of the CASS, with the diagonal of the square being the circle diameter. This array was rotated to 12 unique azimuths at 15° intervals. Reference measurements of the strikes of failure planes were made using a Brunton compass and photographs at adjacent bedrock exposures. Verification of results was done by comparing the geophysical results and the measured strikes and dips of the nearby exposures of the joint systems. Computer software analyses of the results showed coincidence of the tests results with the strike measurements in some areas, whereas others did not. Some of the methods are very sensitive to variations in thickness and water saturation of the overburden. These effects, as well as lateral resistivity gradients in the bedrock and overburden can apparently cause false indications of fracture systems.
|Advisor:||Sauck, William A.|
|Commitee:||Abudayyeh, Osama, Kominz, Michelle, Sauck, William A., Sultan, Mohamed|
|School:||Western Michigan University|
|School Location:||United States -- Michigan|
|Source:||DAI-B 80/08(E), Dissertation Abstracts International|
|Keywords:||Azimuthal seismic array, Electrical resistivity, Engineer geology, Fractures, Joints|
Copyright in each Dissertation and Thesis is retained by the author. All Rights Reserved
The supplemental file or files you are about to download were provided to ProQuest by the author as part of a
dissertation or thesis. The supplemental files are provided "AS IS" without warranty. ProQuest is not responsible for the
content, format or impact on the supplemental file(s) on our system. in some cases, the file type may be unknown or
may be a .exe file. We recommend caution as you open such files.
Copyright of the original materials contained in the supplemental file is retained by the author and your access to the
supplemental files is subject to the ProQuest Terms and Conditions of use.
Depending on the size of the file(s) you are downloading, the system may take some time to download them. Please be