A limestone mine in Ohio has had instability problems that have led to massive roof falls extending to the surface. This study focuses on the role that weak, moisture-sensitive floor has in the instability issues.Prev...A limestone mine in Ohio has had instability problems that have led to massive roof falls extending to the surface. This study focuses on the role that weak, moisture-sensitive floor has in the instability issues.Previous NIOSH research related to this subject did not include analysis for weak floor or weak bands and recommended that when such issues arise they should be investigated further using a more advanced analysis. Therefore, to further investigate the observed instability occurring on a large scale at the Ohio mine, FLAC3 D numerical models were employed to demonstrate the effect that a weak floor has on roof and pillar stability. This case study will provide important information to limestone mine operators regarding the impact of weak floor causing the potential for roof collapse, pillar failure, and subsequent subsidence of the ground surface.展开更多
When roadways are constructed above or adjacent to heavily mined regions, the ground subsidence caused by pillar collapse inflicts severe damage on these roadways. In this study, some surface subsidence events were fi...When roadways are constructed above or adjacent to heavily mined regions, the ground subsidence caused by pillar collapse inflicts severe damage on these roadways. In this study, some surface subsidence events were first reviewed to present roof caving characteristics caused by pillar failure. The bearing characteristic and failure pattern of a single pillar with or without effect of discontinuity were further numerically simulated using distinct element code(3 DEC). It was found that the spalling of pillar or slippage of discontinuity would damage the bearing capacity of pillar during the failure process. The stress at the pillar core could be greater than uniaxial compressive strength of the pillar. However, when a discontinuity runs through a pillar, the slippage of discontinuity would significantly degrade the bearing capacity of the pillar. In pillar support system, if any pillar unexpectedly degrades or loses its bearing capacity, the load transferred from the degraded pillar acts on neighboring pillars, and the shear force also increases at relevant positions. However, the roof cutting and surface subsidence characteristics would perform in different patterns. In some cases, surface subsides slowly;in the worst scenario, shock bump may be induced by pillar and roof collapse.展开更多
基金conducted as part of the research program of the Office of Mine Safety and Health Research of the National Institute for Occupational Safety and Health(NIOSH)
文摘A limestone mine in Ohio has had instability problems that have led to massive roof falls extending to the surface. This study focuses on the role that weak, moisture-sensitive floor has in the instability issues.Previous NIOSH research related to this subject did not include analysis for weak floor or weak bands and recommended that when such issues arise they should be investigated further using a more advanced analysis. Therefore, to further investigate the observed instability occurring on a large scale at the Ohio mine, FLAC3 D numerical models were employed to demonstrate the effect that a weak floor has on roof and pillar stability. This case study will provide important information to limestone mine operators regarding the impact of weak floor causing the potential for roof collapse, pillar failure, and subsequent subsidence of the ground surface.
基金Projects(51838001, 51878070, 51904101) supported by the National Natural Science Foundation of ChinaProject(2019SK2171) supported by the Key Research and Development Program of Hunan Province, ChinaProject(kfj190402) supported by the Open Fund of Engineering Research Center of Catastrophic Prophylaxis and Treatment of Road & Traffic Safety of Ministry of Education(Changsha University of Science & Technology), China。
文摘When roadways are constructed above or adjacent to heavily mined regions, the ground subsidence caused by pillar collapse inflicts severe damage on these roadways. In this study, some surface subsidence events were first reviewed to present roof caving characteristics caused by pillar failure. The bearing characteristic and failure pattern of a single pillar with or without effect of discontinuity were further numerically simulated using distinct element code(3 DEC). It was found that the spalling of pillar or slippage of discontinuity would damage the bearing capacity of pillar during the failure process. The stress at the pillar core could be greater than uniaxial compressive strength of the pillar. However, when a discontinuity runs through a pillar, the slippage of discontinuity would significantly degrade the bearing capacity of the pillar. In pillar support system, if any pillar unexpectedly degrades or loses its bearing capacity, the load transferred from the degraded pillar acts on neighboring pillars, and the shear force also increases at relevant positions. However, the roof cutting and surface subsidence characteristics would perform in different patterns. In some cases, surface subsides slowly;in the worst scenario, shock bump may be induced by pillar and roof collapse.
