A discontinuum modelling approach for investigation of Longwall Top Coal Caving mechanisms

• Published in: International journal of rock mechanics and mining sciences (Oxford, England : 1997) Vol. 106; pp. 84 - 95
• Main Authors: Le, Tien Dung, Oh, Joung, Hebblewhite, Bruce, Zhang, Chengguo, Mitra, Rudrajit
• Format: Journal Article
• Language: English
• Published: Berlin Elsevier Ltd 01.06.2018; Elsevier BV
• Subjects: Calibration; Caves; Caving mechanism; Coal; Coal mines; Coal mining; Discontinuum modelling; Impact analysis; Longwall mining; Longwall Top Coal Caving; Mathematical models; Mining; Mining accidents & safety; Mining industry; Occupational safety; Overburden; Parameter identification; Rock mechanics; Rocks; Rupture; Strata; Stress analysis; Stress concentration; Stress distribution; Stress state; Top coal cavability; Longwall Top Coal Caving; Discontinuum modelling; Top coal cavability; Caving mechanism
• ISSN: 1365-1609; 1873-4545
• DOI: 10.1016/j.ijrmms.2018.04.025

This paper presents a discontinuum modelling approach to investigate Longwall Top Coal Caving (LTCC) behaviour including stress distribution, coal and rock failures, top coal caving and roof strata rupture, and to analyse the impact of overburden movement on top coal caving. The current model ia successful in using plastic material in a discontinuum code for intact rocks. The model scale is large enough to capture the critical features of LTCC, including steady-state caving of top coal and repeatable periodic weighting of roof strata. The applicability of the numerical model was assessed by calibration with field measurements obtained from a longwall mine site. The numerical study found that the stress distribution caused by LTCC mining is in general similar to that caused by conventional longwall mining; top coal predominantly fails in shear whereas roof rock mostly fails in tension; top coal starts to cave in stress caving while main roof strata first rupture in crushing mode; and roof strata weightings periodically increase and decrease top coal cavability. The findings of this study should assist engineers in better understanding fundamental rock mechanics associated with LTCC, identifying key geotechnical parameters dominating caving behaviour, and managing top coal productivity and mine safety involved in LTCC operation. •Plastic material is used in UDEC for modelling Longwall Top Coal Caving (LTCC).•Stress distribution in LTCC is similar to that in conventional longwall method.•Top coal and roof rock predominantly fail in shear and tension, respectively.•The changes of top coal cavability are consistent with periodic roof strata weightings.