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Yu W.-J.,Hunan University of Science and Technology | Wang W.-J.,Hunan University of Science and Technology | Wu Z.-J.,Qujiang Coal Developing Co Ltd
Journal of Coal Science and Engineering | Year: 2012

The system research aimed at activation laws caused by coal mining in fault footwall based on the rock strata mechanics theory in this paper. According to the three-belt characteristics of overlying strata above mined-out area, the fault activation effect was divided into the following three periods: the initial activation, the excessive activation and the ultimate activation. Corresponding activation criterion was also deduced by the mechanics theory. Results of engineering example and numerical analysis show that the activation criterion can reflect the activation laws of fault caused by coal mining. © The Editorial Office of Journal of Coal Science and Engineering (China) and Springer-Verlag Berlin Heidelberg 2012.

Yu W.-J.,Hunan University of Science and Technology | Wang W.-J.,Hunan University of Science and Technology | Wen G.-H.,Qujiang Coal Developing Co Ltd | Zhang N.,Hunan University of Science and Technology | And 2 more authors.
Yantu Gongcheng Xuebao/Chinese Journal of Geotechnical Engineering | Year: 2012

According to large deformation problems of compound-roof coal roadway under high stress, Qujiang Coal Mine in Jiangxi Province is taken as an example, and field survey, theoretical analysis and industrial test are performed. At first, the field survey shows that the mine has features of a typical three-high mine. Because the top anchors and side cables can be brought into full play, the whole supporting system of roadway loses balance and fails. Then, the mechanical function of the coal roadway is studied. It is concluded that the mechanical function is a gradual process, its deformation power comes from roof pressure, and the large deformation of floor is an important failure symbol. Moreover, on the basis of stress characteristics, it is suggested that the roof should be taken as the key supporting part, its integrity should be maintained, and the self-bearing ability of strata should be improved. The comprehensive control technology with the main body of prestress truss and anchor rope and the accessory body of cable + anchor + mesh reinforcement is proposed. Practice shows that the deformation of a supported roadway by means of the comprehensive control technology is markedly improved. The monitoring indicates that the relative convergence rate of sides is less than 1.7 mm/d after 91 days, and the relative convergence rate between roof and floor is greatly reduced, with the maximum value being 297 mm and the rate being less than 1.4 mm/d. So, the whole roadway is in stable status.

Wang W.,Hunan University of Science and Technology | Luo L.,Hunan University of Science and Technology | Huang W.,Qujiang Coal Developing Co Ltd | Qu Y.,Hunan University of Science and Technology | And 2 more authors.
Caikuang yu Anquan Gongcheng Xuebao/Journal of Mining and Safety Engineering | Year: 2014

With the traditional method, large-area supporting failure often arises in anchor cable which causes the result that the maintenance of roadway is very difficult and the cost is high in thick soft-weak roof of deep coal roadway. Through field investigation and theoretical analysis, the factors of anchor cable supporting failure have been studied. The study indicates that the main reasons of anchor cable supporting failure are deformation of cable holes during constructive process in thick soft immediate roof and anchor agent damage during installation. Accordingly, the new design method of anchor cable parameters applying to thick soft immediate roof is proposed. The results show that the length of anchor cable in accordance with the new method is shortened and the anchoring force is improved greatly, and therefore the maintenance of roadway is improved significantly.

Yu W.-J.,Hunan University of Science and Technology | Wang W.-J.,Hunan University of Science and Technology | Huang W.-Z.,Qujiang Coal Developing Co Ltd | Wu H.,Hunan University of Science and Technology
Meitan Xuebao/Journal of the China Coal Society | Year: 2014

Aiming at many problems about deformation and failure of high stress and soft rock roadway, the -850 m main haulage way of Qujiang Mine was taken as an example to study the deformation mechanism and rework control technology. Firstly, deformation and failure situations of seven typical sections in the roadway were surveyed, it is found that main deformation and failure forms include two sides' extrusion, side wall tensional fracture, U section steel distortion, floor heave and roof caving. Results of X diffraction experiment and internal failure detection test show that surrounding rock contains many argillaceous mineral and formed larger loose circles (about 4 m). And then, Barton Classification Q value, Geological Mechanics RMR value and Loose Circle value were used to classify stability of all surveyed roadway sections including V, IV and III class. These three class roadway classified accordingly into collapsed roadway, special roadway and standard roadway, and put forward respectively preliminary supporting projects. Lastly, engineering analogy, rock classification, section area checking and anchorage length calculation were adapted to analyze anchor or cable length of rework roadway, row & line space, strength, diameter and anchorage length. Therefore, the comprehensive support method with "bolt+metal net+gunite covering+anchor+grouting+floor anchor" was selected to rework -850 m main haulage way. The application shows that sides convergences of roadway no more than 66 mm after 147 days, roof and floor convergences less than 119 mm and late convergence rates less than 1 mm/d.

Yu W.-J.,Hunan University of Science and Technology | Wang W.-J.,Hunan University of Science and Technology | Zhang N.,Hunan University of Science and Technology | Huang W.-Z.,Qujiang Coal Developing Co Ltd | And 3 more authors.
Zhongguo Kuangye Daxue Xuebao/Journal of China University of Mining and Technology | Year: 2012

The mechanical deformation of a thick, compound roof in a deep hole was analyzed to solve the global problem of rock deformation. Field surveys and theoretical research on thick, compound roof structures addressed the main causes of global deformation. These very thick roofs have low mechanical strength and multiple, weak layers within them. The effective length of the anchors did not reach into the stronger part of the rock. Three primary zones of deformation include the caving zone, the cracking zone within the separated strata when sagging appears, and a circular instability involving the roof and both sides or the roof and small pillars. A truss anchor beam method of control is presented. Field tests monitoring an installed restraint show that this technology, with its highly stiff truss anchor beams, provide better support than the original bolt and anchor method. The observed deformation is 541 mm less than with the original support method.

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