The direct and accurate estimations of coal thicknesses are prerequisites for intelligent mining practices. One of the most effective methods for detecting the distributions of coal thicknesses in coal mining panels is the in-seam seismic (ISS) method. In the present study, after examining the formation processes and propagation characteristics of refracted P-waves in ISS data, it was concluded that the refracted P-waves in coal seams are mainly formed by the multiple transmission and reflection of the P-waves between the coal and rock interfaces of roof and floor at critical angles. This results in the refracted P-waves having strong periodicity, and these periods are proportional to the coal thicknesses. This study adopted numerical simulation models with different coal thicknesses, and the aforementioned periodicity characteristics were examined. It was found that the coal seam thicknesses could be calculated using the periods of the refracted P-waves. However, in thin- or medium-thick coal seams, it was found that multiple transmitted P-waves overlapped and the periods could not be read directly. Therefore, in order to solve this problem, this study composed source wavelets with the main frequency of the source signals and then composite synthetic P-waves by convoluting the source wavelets with the sequences of various coal thicknesses. The suitable estimated coal thickness corresponded to the minimum value of the errors between the synthetic and actual refracted P-waves. An experiment was conducted in the No. 42224 panel of the Chaigou Coal Mine in order to validate the proposed method. The experimental results revealed that the estimated coal thicknesses from the refracted P-waves were consistent with the actual geologic conditions in the coal mine. Due to the fact that the refracted P-waves arrive earlier than other waves in seismic records, the refracted P-waves could be easily identified and processed. Overall, the proposed method was found to be a simple application process for accurate coal thickness estimations.
This is a preview of subscription content, log in to check access.
Buy single article
Instant access to the full article PDF.
Tax calculation will be finalised during checkout.
Buchanan DJ (1978) The propagation of attenuated SH channel waves. Geophys Prospect 26(1):16–28
Gritto R (2003) Subsurface void detection using seismic tomographic imaging. Lawrence Berkeley National Laboratory, Berkeley
He W, Ji G, Dong S et al (2017) Theoretical basis and application of vertical Z-component in-seam wave exploration. J Appl Geophys 138:91–101
Hu Z, Zhang P, Xu G (2018) Dispersion features of transmitted channel waves and inversion of coal seam thickness. Acta Geophys 66(5):1001–1009
Ji G, Cheng J, Hu J (2014) In-seam wave imaging using attenuation coefficient: method and application. J China Coal Soc 39(S2):471–475 (in Chinese)
Krey TC (1963) Channel waves as a tool of applied geophysics in coal mining. Geophysics 28(5):701–714
Liu S, Zhang J, Li C (2019) Method and test of mine seismic multi-wave and multi-component. J China Coal Soc 44(01):271–277 (in Chinese)
Liu S, Zhao W, Gao S (2019) Experimental study on coal seam thickness measurement of ultra-wide band ground penetrating radar. Coal Sci Technol 47(08):207–212 (in Chinese)
RÄDer D, Schott W, Dresen L et al (1985) Calculation of dispersion curves and amplitude-depth distributions of Love channel waves in horizontally layered media. Geophys Prospect 33:800–816
Regueiro SJ (1990) Seam waves: what are they used for? Part 2. Lead Edge 9(8):32–34
Schott W, Waclawik P (2015) On the quantitative determination of coal seam thickness by means of in-seam seismic surveys. Can Geotech J 52(10):1496–1504
Sheriff RE, Geldart LP (1995) Exploration seismology, 2nd edn. Cambridge Univ. Press, Cambridge
Wang B, Liu S, Jiang Z et al (2011) Advanced forecast of coal seam thickness variation by integrated geophysical method in the laneway. Procedia Eng 26:335–342
Wang G, Pang Y, Ren H (2020a) Intelligent coal mining pattern and technological path. J Min Strata Control Eng 2(01):5–19 (in Chinese)
Wang J, Liu Z, Niu H (2020b) Study on influence of collapse columns on refracted waves between coal seam and rocks and corresponding tomography method. Coal Sci Technol 48(02):214–219 (in Chinese)
Yancey DJ, Imhof MG, Feddock JE et al (2007) Analysis and application of coal-seam seismic waves for detecting abandoned mines. Geophysics 72(5):M7–M15
Zhang J, Liu S, Wang B et al (2019) Response of triaxial velocity and acceleration geophones to channel waves in a 1-m thick coal seam. J Appl Geophys 166(166):112–121
Zhu M, Cheng J, Cui W et al (2019) Comprehensive prediction of coal seam thickness by using in-seam seismic surveys and Bayesian kriging. Acta Geophys 67(3):825–836
This research has been performed under the National Key Research and Development Plan of China (No. 2018YFC0807804) and National Natural Science Foundation of China (No. 41974209).
Conflict of interest
The authors declare that they have no conflict of interest.
Editorial Responsibility: Michal Malinowski (CO-EDITOR-IN-CHIEF)/Rafał Czarny (ASSOCIATE EDITOR).
About this article
Cite this article
Liu, Z., Wang, J. Periods of refracted P-waves in coal seams and their applications in coal thickness estimations. Acta Geophys. 68, 1753–1762 (2020). https://doi.org/10.1007/s11600-020-00505-1
- Refracted P-wave
- Coal seam thickness
- In-seam seismic