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Discontinuous Modelling of Stratum Cave-in in a Longwall Coal Mine in the Arctic Area

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Abstract

This paper presents a discontinuous numerical approach for studying roof cave-in mechanisms and obtaining the required support capacity of longwall shields in a case study site, the Svea Nord coal mine in Svalbard. The block size in the roof strata and the mechanical parameters of the discontinuities for the numerical model were obtained through back-calculations. The back-calculations were conducted with a statistical method of design of experiment. Numerical simulations revealed that voussoir jointed beams are formed before the first cave-in occurs. The maximum deflection of a roof stratum in the study site prior to the first cave-in is about 70 % of the stratum thickness. The maximum span of the roof strata prior to the first cave-in depends upon the in situ horizontal stress state. The roof beams have a large stable span when they are subjected to high horizontal stress; but horizontal stress would increase the possibility of rock crushing in deflected roof beams. The simulations and field measurements show no periodic weighting on the longwall shields in the study site. Stiff and strong roof beams would result in large first and periodic cave-in distances. As a consequence of having large cave-in distances, the longwall shields must have high load capacity, which can be calculated by the presented numerical approach.

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Acknowledgments

The authors would like to thank the Svea Nord mine for their permission to use the mine data. Particular thanks are given to Mr. Tomas Warnqvist for his help during data collection from the longwall shields.

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Authors and Affiliations

  1. Department of Geology and Mineral Resources Engineering, Norwegian University of Science and Technology (NTNU), Trondheim, Norway

    Mahdi Shabanimashcool & Charlie C. Li

  2. Group of Engineering Geology and Geophysics, Department of Land and Water Resource Engineering, Royal Institute of Technology, Stockholm, Sweden

    Lanru Jing

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  1. Mahdi Shabanimashcool
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  2. Lanru Jing
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  3. Charlie C. Li
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Correspondence to Mahdi Shabanimashcool.

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Shabanimashcool, M., Jing, L. & Li, C.C. Discontinuous Modelling of Stratum Cave-in in a Longwall Coal Mine in the Arctic Area. Geotech Geol Eng 32, 1239–1252 (2014). https://doi.org/10.1007/s10706-014-9795-y

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  • DOI: https://doi.org/10.1007/s10706-014-9795-y

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