Evaluation of European empirical methods for subsidence in US coal fields
The intent of this study was to search out and evaluate those empirical methods of characterizing subsidence used in Europe. We need to critically access the applicability of these methods to the emerging US longwall mining practice. European methods consist essentially of (1) the graphical methods of the United Kingdom (UK), which are perhaps the best known here because of the extensive compilation of case histories by the National Coal Board (NCB), and (2) the continental methods based upon mathematical fits in the form of profile or influence functions. Initial phases of our study concentrate upon the graphical methods and the profile functions. NCB practice pertains to the longwall mining of flat lying deposits in the UK, frequently in areas of previous intensive mining of adjacent coal mineral seams. Profile functions center about two antisymmetric forms, the error integral found successful in the coal fields of Upper Silesia (Poland) and the trigonometric found successful in the Donets (USSR) coal fields. In using the empirical methods, it is essential that we recognize certain details of the subsidence trough and distinguish them. A fundamental difference occurs between those profiles which develop at right angles to the mining direction and those that develop parallel to the mining direction. We conclude that the graphical methods representing UK experience are not appropriate for the Illinois longwall mine investigated. The UK subsidence profiles are not as steep as the Illinois observations, i.e., have lower peak strains, perhaps due to the multiple seam workings common in the UK. The two profile functions examined, however, were fairly good fits to the Illinois subsidence data; the subsidence parameters from these functions were consistent between the two panels and can be used to distinguish profile types.
- Research Organization:
- Sandia Labs., Albuquerque, NM (USA)
- DOE Contract Number:
- EY-76-C-04-0789
- OSTI ID:
- 5531330
- Report Number(s):
- SAND-79-2355C; CONF-800507-1
- Resource Relation:
- Conference: Rock mechanics symposium, Rolla, MO, USA, 27 May 1980
- Country of Publication:
- United States
- Language:
- English
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