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Minerals 2015, 5(4), 758-777; https://doi.org/10.3390/min5040523

Numerical Analysis and Experimental Study of Hard Roofs in Fully Mechanized Mining Faces under Sleeve Fracturing

1
School of Civil Engineering and Architecture, Anhui University of Science and Technology, Huainan 232001, China
2
School of Natural and Built Environments, University of South Australia, Adelaide, SA 5095, Australia
*
Authors to whom correspondence should be addressed.
Academic Editor: Samuel Frimpong
Received: 2 September 2015 / Revised: 6 November 2015 / Accepted: 10 November 2015 / Published: 20 November 2015
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Abstract

Sudden falls of large-area hard roofs in a mined area release a large amount of elastic energy, generate dynamic loads, and cause disasters such as impact ground pressure and gas outbursts. To address these problems, in this study, the sleeve fracturing method (SFM) was applied to weaken a hard roof. The numerical simulation software FLAC3D was used to develop three models based on an analysis of the SFM working mechanism. These models were applied to an analysis of the fracturing effects of various factors such as the borehole diameter, hole spacing, and sleeve pressure. Finally, the results of a simulation were validated using experiments with similar models. Our research indicated the following: (1) The crack propagation directions in the models were affected by the maximum principal stress and hole spacing. When the borehole diameter was fixed, the fracturing pressure increased with increasing hole spacing. In contrast, when the fracturing pressure was fixed, the fracturing range increased with increasing borehole diameter; (2) The most ideal fracturing effect was found at a fracturing pressure of 17.6 MPa in the model with a borehole diameter of 40 mm and hole spacing of 400 mm. The results showed that it is possible to regulate the falls of hard roofs using the SFM. This research may provide a theoretical basis for controlling hard roofs in mining. View Full-Text
Keywords: sleeve fracturing method; hard roof; impact ground pressure; deep mines sleeve fracturing method; hard roof; impact ground pressure; deep mines
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Zheng, Z.; Xu, Y.; Li, D.; Dong, J. Numerical Analysis and Experimental Study of Hard Roofs in Fully Mechanized Mining Faces under Sleeve Fracturing. Minerals 2015, 5, 758-777.

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