National Key Laboratory of Gas Disaster Detecting

Laboratory of, China

National Key Laboratory of Gas Disaster Detecting

Laboratory of, China

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Zhang Z.,National Key Laboratory of Gas Disaster Detecting | Zhang Z.,China Coal Technology and Engineering Co.
Advanced Materials Research | Year: 2013

Firstly a GM(1,1) is built to get the dynamic base line for the coal bed methane dynamic productivity of coal mine area. Secondly on the basis of the GM(1,1), Markov chain is applied to achieve state transition probability matrix. Thirdly the coal bed methane dynamic productivity of coal mine area interval is forecasted and analyzed in the form of probability by the system state classification, the calculation of the residue between true value and model fitting value and the standardization of deviation of the residue. It's proved in theory and practice that the forecast results not only are more reliable but also can help the decision maker with grasping the coal bed methane dynamic productivity of coal mine area development tendency in general and making proper decision. Results show that the Grey Markov Model has higher accuracy than that of GM(1,1) model. © (2013) Trans Tech Publications, Switzerland.


Liu Y.,National Key Laboratory of Gas Disaster Detecting | Liu Y.,China Coal Technology and Engineering Co. | Liu Y.,Chongqing University
Procedia Engineering | Year: 2011

Through the experiments investigation on complete stress-strain of coal and the permeability of coal under different stress and gas pressures, the rules of permeability of coal samples under different conditions and the corresponding permeability evolution equation were established. The results show that the permeability of coal samples under certain gas and axial pressure will exponentially decrease when the confining pressure increase. The gas flow in coal has significant Klinkenberg effect. As the volume stress increase, the scope of Klinkenberg effect can also become larger. The relationship of confining pressure & permeability and gas pressure & permeability were obtained by fitting experimental data. Base on permeability test of complete stress-strain, we recognized that the curves between gas permeability and strain under different confining pressure have the similar change trends. Changes of permeability are closely related to the damage evolution of coal. According to the characteristics of permeability curves, considering the integrated effect of confining pressure, axial compression, and gas pressure, the permeability evolution equations of complete stress-strain was established with effective stress. © 2011 Published by Elsevier Ltd.


Zhang S.-T.,China Coal Technology and Engineering Co. | Zhang S.-T.,National Key Laboratory of Gas Disaster Detecting
Procedia Engineering | Year: 2011

The calculated methane content keeps away from real loss methane content with the increasing of loss time and initial desorption velocity data. Small size coal sample's methane absorption and desorption experimental study is carried out under the condition of a certain methane adsorption balance pressure and constant temperature, which the small size coal sample is collected from different coal mines. The experimental data is studied with the methane desorption law of Sun Chong-Xu formula (Q=ati ). Relations among coal sample's methane desorption quantity, exposure time and methane desorption velocity are studied. Then eigenvalues (i) in desorption law (Q=ati) of coal samples with different exposure time is calculated. So the same group coal samples' Eigenvalues calculated with different exposure time are studied. This study provides according for small size coal sample's methane loss value accurate calculation. © 2011 Published by Elsevier Ltd.


Lei Y.,China Coal Technology and Engineering Co. | Wu W.B.,National Key Laboratory of Gas Disaster Detecting | Wu W.B.,China Coal Technology and Engineering Co.
Advanced Materials Research | Year: 2014

Mathematical model based on elasticity is not suitable for soft seam hydraulic fracturing mechanism study because its intensity is small, Poisson's ratio is relatively large, and it's prone to plastic deformation. Based on plastic mechanics, the theory of large deformation and fracture mechanics theory, hydraulic fracturing of soft coal seam is divided into three phases, namely, coal bed compaction, fracture initiation and crack propagation from the view of the deformation mechanism, the occurring and developing mechanism. The initiation pressure of soft seams considered strain softening character after plastic deformation is obtained on the basis of above. The result shows that the initiation pressure is related to elastic modulus, Poisson's ratio, the angle of internal friction and residual strength. Elastic modulus is inversely proportional to the initiation pressure, the greater its value, the smaller the initiation pressure; but Poisson's ratio, the angle of internal friction and the residual strength and fracture initiation pressure is directly proportional relationship, the greater its value, since the smaller the crack pressure. © (2014) Trans Tech Publications, Switzerland.


Wang B.,National Key Laboratory of Gas Disaster Detecting | Wang B.,China Coal Technology and Engineering Co.
Advanced Materials Research | Year: 2014

In order to better implement ratio production of coaly similar material, make use of research results of existing similar materials, consult domestic and foreign documents, and combined with the needs of their own experiment, determine the requirements for coaly similar material, propose a selective condition of similar raw materials, and according to the condition determining a selective content and range of similar raw material. Compared with the advantages and disadvantages of uniform design method and the orthogonal experiment design, put forward the corresponding experimental design, and its uniform dispersion was studied, the research show that the use of uniform design method that used in the ratio and manufacture of coaly similar material, which is very reasonable, its research results provide the basis and foundation for the future experimental research of similar material. © (2014) Trans Tech Publications, Switzerland.


Dai L.C.,National Key Laboratory of Gas Disaster Detecting | Dai L.C.,China Coal Technology and Engineering Co.
Advanced Materials Research | Year: 2014

In order to study the coal and gas outburst similar simulation experiment, coal similar material was made up based on the similarity theory. Based on the previous similar material study, the cement, sand, water, activated carbon and coal powder was selected as the raw material of similar material. Meanwhile similar material matching program with 5 factors and 6 levels was designed by using Uniform Design Method. And the physical and mechanical properties of the similar material compressive strength was measured under different proportions circumstances. The relationship between similar material and the raw materials was analyzed. The results show that choosing different materials can compound different similar materials with different requirements. And the water-cement ratio plays a decisive influence on the compressive strength of similar material. The compressive strength of similar material decreases linearly when the water-cement ratio increases. © (2014) Trans Tech Publications, Switzerland.


Lei Y.,China Coal Technology and Engineering Co. | Wu W.B.,National Key Laboratory of Gas Disaster Detecting | Wu W.B.,China Coal Technology and Engineering Co.
Applied Mechanics and Materials | Year: 2014

Base on the hydraulic fracturing field test in soft coal seam, the rule which the cutting quantity is added and the drilling gas desorption index K1 is decreased, is analyzed from the perspective of physical-mechanical properties and adsorption-desorption law is changed, etc. And gas adsorption and desorption law was analyzed using the theory of two-phase flow, to determine the effect after fracturing coal extraction is improved and the main reason for reducing the outburst. © (2014) Trans Tech Publications, Switzerland.


Wang T.,Wuhan University | Zhou W.,Wuhan University | Chen J.,National Key Laboratory of Gas Disaster Detecting | Xiao X.,Wuhan University | And 2 more authors.
International Journal of Coal Geology | Year: 2014

The purpose of hydraulic fracturing is to improve the gas permeability of a coal seam by the high-pressure injection of fracturing fluid into cracks. This paper simulates the hydraulic fracturing of a coal seam, investigates relevant parameters and analyzes the connection between macroscopic mechanical parameters and mesoscopic mechanical parameters based on two-dimensional particle flow code (PFC2D). Furthermore, the influence of macroscopic mechanical properties on the initiation and size of cracks is studied based on various combinations of particle flow calculations. Empirical formulae for the breakdown pressure and fracture radius are derived. Moreover, the effect of the injection parameters on crack propagation is computed and analyzed, after which the relevant empirical formula is proposed. Finally, numerical simulation of the working face N3704 at Yuyang Coal Mine (YCM) is conducted, and the comparison of results from simulation, empirical formulae and field observation is investigated. The research findings of this paper may provide a reference for selecting injection parameters and forecasting the effect in practical hydraulic fracturing applications. © 2013 Elsevier B.V.


Zhang Z.,National Key Laboratory of Gas Disaster Detecting | Zhang Z.,China Coal Research Institute
Procedia Engineering | Year: 2011

Using gas-diffusion experimental installation created by Chongqing institute of coal science research institute, in different pressure conditions, studied the rule of gas diffusion in tectonically coal. Got the characteristics of the gas diffusion in tectonically coal by analysis of the experimental data, and provided the basis for the gas outburst prediction and estimate the gas emission on the working face. © 2011 Published by Elsevier Ltd.


Mao X.H.,China Coal Research Institute | Mao X.H.,National Key Laboratory of Gas Disaster Detecting
Advanced Materials Research | Year: 2013

A new energy absorption device composed of the foam aluminum and steel plate is introduced here, which can prevent the structure by attenuating the over pressure of air-shockwave produced by a gas blast effectively. In order to find out the blast wave pressure attenuation property of a cladding aluminum foam layer and an aluminum foam sandwich layer, the theoretical and numerical methods were used to study them through comparative analyses. Two kinds of typical structures are simulated numerically, which are the structure with one layer of a steel plate and the structure with both a layer of the steel plate and the device respectively. The results of the simulation show that the multilayer composite structure has the excellent capacity to reduce the blast loading and attenuate the over pressure of air-shockwave. the aluminum foam sandwich layer have the ability to attenuate the blast pressure before compressed to solid, and the ability decreases after the aluminum foam was completely compressed. The simulation experimental environment can be established and reference data can be provided for the design of a life-saving ball system by using numerical analysis methods. © (2013) Trans Tech Publications, Switzerland.

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