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Yu B.,Datong Coal Mine Group Company
Journal of Rock Mechanics and Geotechnical Engineering | Year: 2016

Accidents such as support failure and excessive deformation of roadways due to drastic changes in strata behaviors are frequently reported when mining the extra-thick coal seams Nos. 3-5 in Datong coal mine with top-coal caving method, which significantly hampers the mine's normal production. To understand the mechanism of strata failure, this paper presented a structure evolution model with respect to strata behaviors. Then the behaviors of strata overlying the extra-thick coal seams were studied with the combined method of theoretical analysis, physical simulation, and field measurement. The results show that the key strata, which are usually thick-hard strata, play an important role in overlying movement and may influence the mining-induced strata behaviors in the working face using top-coal caving method. The structural model of far-field key strata presents a "masonry beam" type structure when "horizontal O-X" breakage type happens. The rotational motion of the block imposed radial compressive stress on the surrounding rock mass of the roadway. This can induce excessive deformation of roadway near the goaf. Besides, this paper proposed a pre-control technology for the hard roof based on fracture holes and underground roof pre-splitting. It could effectively reduce stress concentration and release the accumulated energy of the strata, when mining underground coal resources with top-coal caving method. © 2016 Institute of Rock and Soil Mechanics, Chinese Academy of Sciences. Source


Yao X.,China University of Mining and Technology | Liu J.,China University of Mining and Technology | Gong G.,China University of Mining and Technology | Gong G.,Beijing Institute of Labor Protection Science | And 3 more authors.
International Journal of Mining Science and Technology | Year: 2013

A series of activated carbons from Taixi anthracite were prepared by steam activation in the presence of KOH and then they were modified by different methods. The regulation of porosity and the modification of surface chemistry were carried out with the aim to improve the benzene adsorption capacity of activated carbon. The influences of KOH and activation process parameters including activation temperature, activation time and steam flow rate on porosity of activated carbon were evaluated, and the effect of modification methods on surface chemistry was investigated. Also, the relationship between benzene adsorption capacity and porosity and surface chemistry was analyzed. Results show that activation temperature is the dominant factor in the activation process; the introduction of KOH into the raw material can enhance the reactivity of char in activation process, meanwhile it shows a negative effect on the porosity development, especially on the mesopore development. Results of FTIR analysis indicate that anthracite-based activated carbon with condensed aromatics and chemically inert oxygen does not present the nature to be surface modified. Besides, benzene adsorption capacity has an approximate linear relationship with surface area and in our preparation, benzene adsorption capacity and surface area of activated carbon are up to 1210 m2/g and 423 mg/g, respectively. © 2013 Published by Elsevier B.V. on behalf of China University of Mining & Technology. Source


Liu C.-Y.,China University of Mining and Technology | Yang J.-X.,China University of Mining and Technology | Yu B.,China University of Mining and Technology | Yu B.,Datong Coal Mine Group Company | Yang P.-J.,China University of Mining and Technology
Meitan Xuebao/Journal of the China Coal Society | Year: 2014

In order to understand the coal face pressure effects from the hard roof group structure breaking and instability, the relation was proved between the hard roof group structure and strata behavior. It investigated the instability characteristics of roof group structure combining the research methods of the theoretical analysis, similar simulation experiment and field measured according to the conditions of hard thick roof group structure under multi gob in Datong coal mining area. It shows that: the roof group structure instability has some certain probability characteristic; multiple parameters Weibull function describes well on instability forms in breaking roof group structure, and establishes the similar roof structure instability rate under the condition of the close distance coal seam group, then gives the roof instability parameters, and analyzes on the goaf roof instability rate in Jurassic coal seam group. It is shown that the roof group structure instability rate have some influence on the face support resistance. Through the mine pressure and support resistance measurement results on the end and central position of the coal face, verify the hard thick roof instability regularity in the No. 15 face of Yongding Village Coal Mine in Datong mining area. Source


Liu J.-R.,Datong Coal Mine Group Company | Kang Q.-T.,North China Institute of Science and Technology
Caikuang yu Anquan Gongcheng Xuebao/Journal of Mining and Safety Engineering | Year: 2013

Affected by complicated factors such as large section, low strength of coal mass, high in-situ stress, rich water roof and Mudstone floor characterized by rheological, swelling and softening property, the roadway in Ma Jialiang Mine soft coal seam encounters heavy rock surrounding support problems of roof sag and floor heave. Consequently, the safe and orderly production was affected seriously. Taking the main air return way as a primary research object, the paper has studied the law of surrounding rock deformation and failure, reasonable section size and shape, support parameters and floor heave control method by means of field measurement, theoretical analysis, numerical simulation and so on. The research shows that micro cambered arch roof, drain-pipe installed in roof, inverted-arch floor, net and bolt support of whole section are the optimum combination of section form and support scheme. The field application tells that the optimized air return way surrounding deformation can be controlled effectively, which meets the requirements of keeping it stable for a long period. The achievements of this research will offer useful data for large section roadway support in soft coal seam. Source


Wu F.,China University of Mining and Technology | Yang J.,China University of Mining and Technology | Yu B.,China University of Mining and Technology | Yu B.,Datong Coal Mine Group Company | Chen X.,China University of Mining and Technology
Zhongguo Kuangye Daxue Xuebao/Journal of China University of Mining and Technology | Year: 2014

In order to study the caving height of goaf roof of thick and extra thick seams, a comprehensive method including theory analysis, numerical calculation, physical simulation and field measurement is used. Results show that the key strata theory can be used for the hard and structural integrity roof. The calculation method of the gob roof caving height, which considers the effects of the roof deflection and the gangue broken expansions, is generally applicable, and the gob roof caving height is found to be impacted by mining thickness, the bulk increase coefficient of broken block in the roof and the limit amount deflection of the mine roof. The caving height of the No. 8105 working face hard roof of Datong Mine Tongxin coal mine are calculated as 143 m and 76-141 m by two theoretical analyses, and the field measurement is 80-120 m, indicating the applicability of these two methods. Source

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