[1] United States Congress Office of Technology Assessment (1981) An Assessment of Development and Production Potential of Federal Coal Leases. Congress of the U.S., Office of Technology Assessment, Washington DC.
[2] EIA, US (2011) International Energy Statistics. https://www.eia.gov/cfapps/ipdbproject/IEDIndex3.cfm?tid=1
[3] Yasitli, B. (2005) 3-D Numerical Modelling of Stresses around a Longwall Panel with Top Coal Caving. Journal of the Southern African Institute of Mining and Metallurgy, 105, 287-300. https://doi.org/10.1016/j.ijrmms.2004.08.007
[4] Karacan, C.?. (2010) Prediction of Porosity and Permeability of Caved Zone in Longwall Gobs. Transport in Porous Media, 82, 413-439. https://doi.org/10.1007/s11242-009-9437-7
[5] Gray, I. (1987) Reservoir Engineering in Coal Seams: Part 1—The Physical Process of Gas Storage and Movement in Coal Seams. SPE Reservoir Engineering, 2, 28-34. https://doi.org/10.2118/12514-pa
[6] Bear, J. (2013) Dynamics of Fluids in Porous Media. Courier Corporation, Chelmsford. https://doi.org/10.1097/00010694-197508000-00022
[7] Gochioco, L.M. (2000) High-Resolution 3-D Seismic Survey over a Coal Mine Reserve Area in the US—A Case Study. Geophysics, 65, 712-718. https://doi.org/10.1190/1.1444770
[8] Chen, T., Wang, X. and Mukerji, T. (2015) In Situ Identification of High Vertical Stress Areas in an Underground Coal Mine Panel Using Seismic Refraction Tomography. International Journal of Coal Geology, 149, 55-66. https://doi.org/10.1016/j.coal.2015.07.007
[9] Cao, A., Dou, L., Cai, W., Gong, S., Liu, S. and Jing, G. (2015) Case Study of Seismic Hazard Assessment in Underground Coal Mining Using Passive Tomography. International Journal of Rock Mechanics and Mining Sciences, 78, 1-9. https://doi.org/10.1016/j.ijrmms.2015.05.001
[10] Si, G., Durucan, S., Jamnikar, S., Lazar, J., Abraham, K., Korre, A., Shi, J.-Q., Zav?ek, S., Mutke, G. and Lurka, A. (2015) Seismic Monitoring and Analysis of Excessive Gas Emissions in Heterogeneous Coal Seams. International Journal of Coal Geology, 149, 41-54. https://doi.org/10.1016/j.coal.2015.06.016
[11] Ge, M., Wang, H., Hardy, H. and Ramani, R. (2008) Void Detection at an Anthracite Mine Using an In-Seam Seismic Method. International Journal of Coal Geology, 73, 201-212. https://doi.org/10.1016/j.coal.2007.05.004
[12] Fimagalli E. ,et al. (1969)Test on Cohesionless Material for Rockfill Dams Journal of the Soil Mechanics and Foundations Division 95, 313-330.
[13] Hardin, B.O. (1985) Crushing of Soil Particles. Journal of Geotechnical Engineering, 111, 1177-1192. https://doi.org/10.1061/(asce)0733-9410(1985)111:10(1177)
[14] Palchik, V. (2002) Influence of Physical Characteristics of Weak Rock Mass on Height of Caved Zone over Abandoned Subsurface Coal Mines. Environmental Geology, 42, 92-101. https://doi.org/10.1007/s00254-002-0542-y
[15] Raymer, L., Hunt, E. and Gardner, J.S. (1980) An Improved Sonic Transit Time-to-Porosity Transform. Proceedings of Society of Petrophysicists and Well-Log Analysts, Houston, 1-13.