Wang X.-F.,China University of Mining and Technology |
Zhang D.-S.,China University of Mining and Technology |
Li G.-J.,Tiefa Coal Industry Group Corporation Ltd. |
Ren T.-X.,University of Wollongong |
Wang X.-D.,Baoji Qinyuan Coal Mining Group Corporation Ltd.
Meitan Xuebao/Journal of the China Coal Society | Year: 2011
Based on the high gassy and low permeability coal seams geo-conditions and developing technology in Tiefa coalfield, the features of mining-induced fractures with different mining orders, gas migration under U model exhaust ventilation, and boreholes layout of methane drainage were studied by means of physical simulation and CFD(Computational Fluid Dynamics) numerical modeling. The results show that mining-induced fractures are mainly generated on the inside of the retreat drift, around 1/3 along the retreat direction and the zone where gas mainly flows range from 30 to 80 m away from the tailgate. Arising from this, it can be derived that the boreholes should be drilled vertically with a distance that is the summation of caved zone height and 1/3 fractured zone height to the coalface roof, the separation distance should be no less than 100~150 m for surface boreholes, and the best location for the boreholes should be with a distance of 1/3~1/2 inclination.
Lin B.-Q.,China University of Mining and Technology |
Li Z.-W.,China University of Mining and Technology |
Zhai C.,China University of Mining and Technology |
Bi Q.,Tiefa Coal Industry Group Corporation Ltd |
Wen Y.-Y.,Tiefa Coal Industry Group Corporation Ltd
Caikuang yu Anquan Gongcheng Xuebao/Journal of Mining and Safety Engineering | Year: 2011
In order to improve the existing pressure relief and permeability increasing technologies, high pressure pulsating hydraulic fracturing technology was put forward on the basis of hydraulic fracturing to solve the current problems of regional gas control in coal mines. The propagation law of pulsating pressure in fractures and the effect of pressure relief and permeability-increasing were investigated by theoretical analysis and field test. The results show that the pulsating hydraulic fracturing can make some physical quantities of coal change repeatedly and produce fatigue failure, which in turn, dredges the pores and enhances the permeability. The effect of pressure relief reaches the best when the pulsating pressure is 24 MPa and the frequency is 20 Hz. The extraction concentration increases by 264.7% after fracturing while the gas flow increases by 245.5%. The values and the change ranges of q and S which are outburst risk indexes reduce obviously. This technology can effectively enhance the affecting range of a single borehole and increase the extraction efficiency. It has a broad industrial application prospects.
Ye Y.-Q.,LIAONING Technical University |
Chen X.-L.,LIAONING Technical University |
Li J.,Tiefa Coal Industry Group Corporation Ltd
Dongbei Daxue Xuebao/Journal of Northeastern University | Year: 2011
The relationships among the sense of general happiness, pressure and psychological health for 461 coal miners were studied via questionnaire survey. The results based on the 442 effective questionnaires shown that there are significant differences in general happiness, pressure and psychological health of coal miners who have different healthy, the interpersonal relationship, the spouse relate and financial circumstance. There are noticeable correlations among general happiness, pressure and psychological health of coal miners. Pressure of coal miners has significant negative correlation with their general happiness and psychological health. Psychological health of coal miners is positively correlated with their general happiness. Pressure and psychological health proved to be a strong predictor of general happiness, which pressure completely mediated the role of psychological health played on general happiness.