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Zhang Y.,China University of Mining and Technology | Wan Z.,China University of Mining and Technology | Li F.,Yanzhou Coal Mining Company Ltd | Zhou C.,China University of Mining and Technology | And 3 more authors.
International Journal of Mining Science and Technology | Year: 2013

Considering the situation that it is difficult to control the stability of narrow coal pillar in gob-side entry driving under unstable overlying strata, the finite difference numerical simulation method was adopted to analyze the inner stress distribution and its evolution regularity, as well as the deformation characteristics of narrow coal pillar in gob-side entry driving, in the whole process from entry driving of last working face to the present working face mining. A new method of narrow coal pillar control based on the triune coupling support technique (TCST), which includes that high-strength prestressed thread steel bolt is used to strain the coal on the goaf side, and that short bolt to control the integrity of global displacement zone in coal pillar on the entry side, and that long grouting cable to fix anchor point to constrain the bed separation between global displacement zone and fixed zone, is thereby generated and applied to the field production. The result indicates that after entry excavating along the gob under unstable overlying strata, the supporting structure left on the gob side of narrow coal pillar is basically invalid to maintain the coal-pillar stability, and the large deformation of the pillar on the gob side is evident. Except for the significant dynamic pressure appearing in the coal mining of last working face and overlying strata stabilizing process, the stress variation inside the coal pillar in other stages are rather steady, however, the stress expansion is obvious and the coal pillar continues to deform. Once the gob-side entry driving is completed, a global displacement zone on the entry side appears in the shallow part of the pillar, whereas, a relatively steady fixed zone staying almost still in gob-side entry driving and present working face mining is found in the deep part of the pillar. The application of TCST can not only avoid the failure of pillar supporting structure, but exert the supporting capacity of the bolting structure left in the pillar of last sublevel entry, thus to jointly maintain the stability of coal pillar. © 2013 Published by Elsevier B.V. on behalf of China University of Mining & Technology. Source


Meng Q.,Xuzhou Normal University | Wang Y.-S.,China University of Mining and Technology | Wang Y.-S.,Yanzhou Coal Mining Company Ltd | Zhou Y.,China University of Mining and Technology
Meitan Xuebao/Journal of the China Coal Society | Year: 2010

A approach to predict spontaneous combustion in caving zone by using rough set and support vector machine(RS-SVM) was proposed. The original sample data were preprocessed with the knowledge reduction algorithm of RS theory, and the redundant condition attributes and conflicting samples were eliminated from the working sample set to reduce space dimension of sample data. Preprocessed sample data were used as training sample data of SVM. With choosing an appropriate kernel function, the SVM parameters were optimized by using variable step search algorithm. Finally, a comparison of the performance of RS-SVM with SVM and neural networks was carried out. The experimental results show that the prediction based on RS-SVM can improve the training speed and precision of classification when the samples are limited. Source


He G.-J.,National Institute for Occupational Safety | Ruan G.-Q.,Yanzhou Coal Mining Company Ltd
Meitan Xuebao/Journal of the China Coal Society | Year: 2011

Based on the characteristics of Zhaolou Coal Mine, analyzed the condition of heat sources at open face, heading face and stope face, and also studied the prevention and control measures against the heat disaster from mine construction to mine production in Zhaolou Coal Mine. The research shows that the open face and heading face are mainly in wall rock radiating, coal face is mainly in electrical equipment and hot-water radiating. Considering from mining design, radiation equipment, operating method and personal protection, Zhaolou Coal Mine used all possible ways such as separate ventilation, mechanical radiation, descensional ventilation, reducing working time and make up brine to control the heat disaster from mine construction to mine production. During the coal mine construction period and transitional period, Zhaolou Coal Mine used some refrigeration technology, such as "ground cooling station-spray equipment to cool wind in mine plenum-cooling the ventilation face/ventilation system" and set up a cooling chamber at the parking place of underground mine to centralized refrigeration. All of these get a good cooling result. Source


Liang D.,China University of Mining and Technology | Jiang Z.,China University of Mining and Technology | Cao D.,Yanzhou Coal Mining Company Ltd
Caikuang yu Anquan Gongcheng Xuebao/Journal of Mining and Safety Engineering | Year: 2016

Based on turbulent flow and non-Darcy flow, the hydraulic conductivity calculating formula was derived by using hydraulic pressure in water injection borehole, length of the water injection part, hydraulic pressure and discharge in monitor borehole. With the test results of coal seam floor's water-pressure in a mine, the difference of hydraulic conductivities under different flow status were analyzed, and it shows that the calculating result of hydraulic conductivity is greatly influenced by flow patterns, and the rock masses' permeability can be changed greatly by hydraulic pressure. The paper provides an effective method for calculation of non-Darcy flow hydraulic conductivity in fracture rocks under turbulent flow conditions. © 2016, China University of Mining and Technology. All right reserved. Source


Huang Z.,China University of Mining and Technology | Jiang Z.,China University of Mining and Technology | Zhu S.,China University of Mining and Technology | Qian Z.,China University of Mining and Technology | Cao D.,Yanzhou Coal Mining Company Ltd
International Journal of Rock Mechanics and Mining Sciences | Year: 2014

The hydraulic behavior of the rock formations under coal floor is an important factor to evaluate the risk of floor water inrush, which is difficultly obtained exactly by laboratory hydraulic tests. For the purpose of obtaining the hydraulic conductivity of the rock formations between deep coal and aquifers and further evaluating the risk of floor water inrush, water injection tests are carried out at Baodian coal mine. Through drilling four boreholes, three water injection tests of three rock formations are carried out and the hydraulic conductivity of the rock formations is calculated. Experimental results analysis shows that the three test rock formations are low-permeability. The hydraulic conductivity propagation with injection pressure can be divided into two phases that include stable change phase and increase phase due to hydraulic fracturing. In addition, the crack connections and propagations model can be used to analyze the change process of hydraulic conductivity of rock formations under water pressure. It is a useful approach for obtaining the hydraulic conductivity of deep rock formation, evaluating the risk of floor water inrush, preventing water inrush and raising the coal mining efficiency in colliery. © 2014 Elsevier Ltd. Source

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