To investigate the resist-decreasing effects of rock bolts on the strength of the rock mass around a roadway,a comparative study has been carried out using the numerical analysis code FLAC3D.An unsupported and a rock ...To investigate the resist-decreasing effects of rock bolts on the strength of the rock mass around a roadway,a comparative study has been carried out using the numerical analysis code FLAC3D.An unsupported and a rock bolt supported model have been built for comparison.Two types of rock mass strength,the uniaxial compressive strength(UCS) and the triaxial compressive strength(TCS) of rock mass have been obtained from each model,using a prepared Fish based on the Mohr-Coulomb criterion.The results indicate that when a roadway is excavated,both the UCS and TCS in a definite local rock mass around the roadway would inevitably decrease,no matter whether the roadway is supported or not.The major decreasing region did not settle in the middle of the roadway surface,but within a deeper horizon into the rock mass.The resist-decreasing effects of rock bolts both on the UCS and the TCS of rock mass around roadway are significant.展开更多
Dust suppression in coal mines is a worldwide problem which has not been solved effectively. The applica-tion of negative pressure secondary dust removal (NPSDR) is a breakthrough in the coal mine safety field. In thi...Dust suppression in coal mines is a worldwide problem which has not been solved effectively. The applica-tion of negative pressure secondary dust removal (NPSDR) is a breakthrough in the coal mine safety field. In this paper,NPSDR technology and ultrasonic dust suppression systems are introduced. High pressure water is supplied to the NPSDR device which is mounted on the shearer. A negative pressure field is formed in the device. At the same time,the dusty air around the shearer drum will be sucked into,and purged from,the NPSDR device by the negative pressure field. An ultrasonic dust suppression system uses water and compressed air to produce micron sized droplets which suppress respirable coal dust effectively. The NPSDR technology can be used for shearer dust suppression while ultra-sonic dust suppression can be applied in areas such as the transportation positions. These dust suppression methods have the following advantages: high efficiency,wide applicability,simple structure,high reliability and low cost.展开更多
Many factors can induce rock burst. Shock energy and shock distance are two key factors affecting rock burst. The 32101 roadway of the Xingcun coal mine, which has a tendency for rock burst, was used as an example. Th...Many factors can induce rock burst. Shock energy and shock distance are two key factors affecting rock burst. The 32101 roadway of the Xingcun coal mine, which has a tendency for rock burst, was used as an example. The dynamic module of Itasca’s FLAC (Fast Lagrangian Analysis of Continua) 2D explicit finite-difference software was used to simulate the roadway’s destruction. The vibration velocity and displacements of the rock surrounding the roadway were modeled for different shock energies and hypocenter distances. The simulation results indicate that the vibration velocity and displacement of rock surrounding the roadway have a quadratic relationship to the shock energy and a power law relationship to the distance of the hypocenter from the roadway. A dynamic view of the process was obtained from a series of "snap-shots" collected at 100 different time steps. This shows an isolating "river" is first formed at the hypocenter. The region above the "river" is a low stress zone while below the "river" a high stress zone exists. This high stress zone surrounds the ribs of the roadway in a "double ear" pattern. Continuous and repeated action of the high stress in the "double ear" shaped zone destroys the roadway.展开更多
基金Project 2006BAK04B02 supported by the National Key Technology Research & Development Program of China
文摘To investigate the resist-decreasing effects of rock bolts on the strength of the rock mass around a roadway,a comparative study has been carried out using the numerical analysis code FLAC3D.An unsupported and a rock bolt supported model have been built for comparison.Two types of rock mass strength,the uniaxial compressive strength(UCS) and the triaxial compressive strength(TCS) of rock mass have been obtained from each model,using a prepared Fish based on the Mohr-Coulomb criterion.The results indicate that when a roadway is excavated,both the UCS and TCS in a definite local rock mass around the roadway would inevitably decrease,no matter whether the roadway is supported or not.The major decreasing region did not settle in the middle of the roadway surface,but within a deeper horizon into the rock mass.The resist-decreasing effects of rock bolts both on the UCS and the TCS of rock mass around roadway are significant.
文摘Dust suppression in coal mines is a worldwide problem which has not been solved effectively. The applica-tion of negative pressure secondary dust removal (NPSDR) is a breakthrough in the coal mine safety field. In this paper,NPSDR technology and ultrasonic dust suppression systems are introduced. High pressure water is supplied to the NPSDR device which is mounted on the shearer. A negative pressure field is formed in the device. At the same time,the dusty air around the shearer drum will be sucked into,and purged from,the NPSDR device by the negative pressure field. An ultrasonic dust suppression system uses water and compressed air to produce micron sized droplets which suppress respirable coal dust effectively. The NPSDR technology can be used for shearer dust suppression while ultra-sonic dust suppression can be applied in areas such as the transportation positions. These dust suppression methods have the following advantages: high efficiency,wide applicability,simple structure,high reliability and low cost.
基金Projects 50490270, 50474068, 50674085 supported by the National Natural Science Foundation of China 2005CB221504 by the National Key FoundationResearch Program of China+2 种基金2006BAK04B02, 2006BAK03B06 by the National Science Program of China NCET-06-0478 by the Ministry of Education New Century Outstanding Person Programming of China2006B002 by the Science Foundation of China University of Mining and Technology
文摘Many factors can induce rock burst. Shock energy and shock distance are two key factors affecting rock burst. The 32101 roadway of the Xingcun coal mine, which has a tendency for rock burst, was used as an example. The dynamic module of Itasca’s FLAC (Fast Lagrangian Analysis of Continua) 2D explicit finite-difference software was used to simulate the roadway’s destruction. The vibration velocity and displacements of the rock surrounding the roadway were modeled for different shock energies and hypocenter distances. The simulation results indicate that the vibration velocity and displacement of rock surrounding the roadway have a quadratic relationship to the shock energy and a power law relationship to the distance of the hypocenter from the roadway. A dynamic view of the process was obtained from a series of "snap-shots" collected at 100 different time steps. This shows an isolating "river" is first formed at the hypocenter. The region above the "river" is a low stress zone while below the "river" a high stress zone exists. This high stress zone surrounds the ribs of the roadway in a "double ear" pattern. Continuous and repeated action of the high stress in the "double ear" shaped zone destroys the roadway.
