1887
Volume 33 Number 6
  • E-ISSN: 1365-2478

Abstract

A

We present dispersion curves, and amplitude‐depth distributions of the fundamental and first higher mode of Love seam waves for two characteristic seam models. The first model consists of four layers, representing a coal seam underlain by a root clay of variable thickness. The second model consists of five layers, representing coal seams containing a dirt band with variable position and thickness. The simple three‐layer model is used for reference.

It is shown that at higher frequencies, depending on the thickness of the root clay and the dirt band, the coal layers alone act as a wave guide, whereas at low frequencies all layers act together as a channel. Depending on the thickness, and position of the dirt band and the root clay, in the dispersion curves of the group velocity, secondary minima grow in addition to the absolute minima. Furthermore, the dispersion curves of the group velocity of the two modes can overlap. In all these cases, wave groups in addition to the Airy phase of the fundamental mode (propagating with minimum group velocity) occur on the seismograms recorded in in‐seam seismic surveys, thus impeding their interpretation. Hence, we suggest the estimation of the dispersion characteristics of Love seam waves in coal seams under investigation preceding actual field surveys.

All numerical calculations were performed using a fast and stable phase recursion algorithm.

Loading

Article metrics loading...

/content/journals/10.1111/j.1365-2478.1985.tb00779.x
2006-04-27
2020-09-21
Loading full text...

Full text loading...

References

  1. Arnetzl, H. and Klinge, U.1982, Erfahrungen mit der Flözwellenseismik bei der Vorfelderkundung, Glückauf118, 658–664.
    [Google Scholar]
  2. Brentrup, F. K., Kerner, C., Klar, J., Knecht, M. and Schott, W.1983, Technologische Forschung und Entwicklung‐Nichtnukleare Energietechnik: Flözwellenseismische Vorfelderkundung mit Hilfe digitaler Meßwerterfassung, Bundesministerium für Forschung und Technologie, Forschungsbericht T 83–222.
    [Google Scholar]
  3. Buchanan, D. J., Davis, R., Jackson, P. J. and Taylor, P. M.1981, Fault location by channel wave seismology in United Kingdom coal seams, Geophysics46, 994–1002.
    [Google Scholar]
  4. Dresen, L. and Freystätter, S.1976, Rayleigh‐channel waves for the in‐seam seismic detection of discontinuities, Journal of Geophysics42, 111–129.
    [Google Scholar]
  5. Dresen, L., Kerner, C. and Kühbach, B.1985, The influence of an asymmetry in the sequence “rock‐coal‐rock” on the propagation of Rayleigh seam‐waves, Geophysical Prospecting33, 519–539.
    [Google Scholar]
  6. Evison, F. F.1955, A coal seam as a guide for seismic energy, Nature176, 1224–1225.
    [Google Scholar]
  7. Freystätter, S. and Dresen, L.1978a, The influence of oblique‐dipping discontinuities on the use of Rayleigh‐channel waves for the in‐seam seismic reflection method, Geophysical Prospecting26, 1–15.
    [Google Scholar]
  8. Freystätter, S. and Dresen, L.1978b, Model seismic experiments on the use of Rayleigh channel waves for the in‐mine seismic detection of discontinuities, in Proceedings of Coal Seam Discontinuities Symposium, D'Appolonia Consulting Engineers, Pittsburg PA , 151–1521.
    [Google Scholar]
  9. Klinge, U., Arnetzl, H., Krey, Th. and Rüter, H.1981, Trends in the detection of coal seam discontinuities by in‐seam seismic techniques, 3rd International Coal Exploration Symposium, Miller‐Freeman, San Francisco , 1–24.
    [Google Scholar]
  10. Krey, Th.1963, Channel waves as a tool of applied geophysics in coal mining, Geophysics28, 701–714.
    [Google Scholar]
  11. Mason, I. M., Buchanan, D. S. and Booer, A. K.1980, Channel wave mapping of coal seams in the United Kingdom, Geophysics45, 1131–1143.
    [Google Scholar]
  12. Rüter, H. and Schepers, R.1979, In‐seam seismics methods for the detection of discontinuities applied to West German coal deposits, in Coal Exploration 2, Argall, G. O. (ed.), Proceedings of the 2nd International Coal Exploration Symposium, Miller‐Freeman, San Francisco , 267–293.
    [Google Scholar]
http://instance.metastore.ingenta.com/content/journals/10.1111/j.1365-2478.1985.tb00779.x
Loading
  • Article Type: Research Article
This is a required field
Please enter a valid email address
Approval was a Success
Invalid data
An Error Occurred
Approval was partially successful, following selected items could not be processed due to error