Theory of low-frequency conductivity probing of roof structures in coal mines


  • Margarete A. Ralston,

  • James R. Wait


Determining electrical ground constants of the earth is an important problem in geophysical probing [Keller, 1971; Wait, 1979] and underground communication system design [Aldredge, 1973]. Several different methods are used to determine the relative permittivity εr and resistivity p or conductivity ó of a stratified earth. As noted in the Institute of Electrical and Electronics Engineers (IEEE) [1974] Standard 356, techniques for determining the electrical constants of the earth are roughly divided into two categories: (1) methods where drill hole access into the earth does not exist or is not required, (2) techniques requiring drill hole access into the earth. Methods using drill holes are primarily for determining electrical ground constants in a local area.

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