Semester

Fall

Date of Graduation

2007

Document Type

Thesis

Degree Type

MS

College

Statler College of Engineering and Mineral Resources

Department

Mining Engineering

Abstract

Safety and production of coal mining operations could be greatly affected by geologic anomalies such as faults, sandstone intrusions, dykes, fracture zones, sudden thinning and severe undulation of the coal seam. Since most of these geologic anomalies in coal seams effect the attenuation rate of electromagnetic signal that passes through them, the radio imaging method (RIM), using a signal in the kilohertz range, is capable of locating the zones of geologic anomalies in underground coal mines with the help of tomographic reconstruction programs. RIM technology is a promising geophysical tool for exploring the geologic anomalies ahead of modern longwall faces, which are normally wider than 1,000 ft. When multiple geologic anomalies co-exist in an area, it is very difficult for RIM technology to differentiate the contributions of each individual anomalous factor. Other problems with RIM technology are the angular spreading and moisture content is not taken into consideration of the surveyed area. To increase the accuracy of RIM technology, spatial spreading testing and a scaled physical model were employed to investigate the capabilities and limitations of RIM technology. To simulate the RIM technology, a Ground Penetration RADAR (GPR) system was modified and a higher frequency signal was used in the scaled physical model. One of the problems using the GPR was that data collected was represented in counts and formulae had to be developed in order to convert the data into volts. Laboratory testing was conducted to assure proper similarities between the actual longwall panel and the scaled physical model. These model tests were done to gain a better quantitative understanding of the propagation of EM signals in the physical model. The testing procedure and data results are presented and quantified.

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