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Yuan L.,National Engineering Research Center for Coal Mine Gas Control | Xue J.-H.,National Engineering Research Center for Coal Mine Gas Control | Liu Q.-S.,CAS Wuhan Institute of Rock and Soil Mechanics | Liu B.,CAS Wuhan Institute of Rock and Soil Mechanics
Meitan Xuebao/Journal of the China Coal Society | Year: 2011

The laboratory experiment, theoretical analysis and numerical simulation were adopted to study the complex geological condition in deep rock roadway of Huainan coal mining area systematically. The classification system of surrounding rock in deep rock roadway of coal mine was put forward. The deformation fracture mechanism and the stability evolution of surrounding rock were analyzed under the complex geological condition of high underground stress, high head seepage pressure and high temperature gradient. And the control theory for stability of deep roadway was proposed: recovery and improvement of stress, strength enhancement, consolidation and restoration of fracture damage zone, transformation of peak stress and enhancement of loading bearing zone. The relative technical measures system and stepped combined control concept were put forward based on the surrounding rock classification. Set of techniques for surrounding rock stability and construction safety control in deep rock roadway of Huainan coal mining area were established. Source

Xue S.,CSIRO | Xue S.,Taiyuan University of Technology | Yuan L.,National Engineering Research Center for Coal Mine Gas Control | Wang J.,Taiyuan University of Technology | And 2 more authors.
International Journal of Coal Science and Technology | Year: 2015

An outburst of coal and gas is a major hazard in underground coal mining. It is generally accepted that an outburst occurs when certain conditions of stress, coal gassiness and physical–mechanical properties of coal are met. Outbursting is recognized as a two-step process, i.e., initiation and development. In this paper, we present a fully-coupled solid and fluid code to model the entire process of an outburst. The deformation, failure and fracture of solid (coal) are modeled with the discrete element method, and the flow of fluid (gas and water) such as free flow and Darcy flow are modeled with the lattice Boltzmann method. These two methods are coupled in a two-way process, i.e., the solid part provides a moving boundary condition and transfers momentum to the fluid, while the fluid exerts a dragging force upon the solid. Gas desorption from coal occurs at the solid–fluid boundary, and gas diffusion is implemented in the solid code where particles are assumed to be porous. A simple 2D example to simulate the process of an outburst with the model is also presented in this paper to demonstrate the capability of the coupled model. © 2015, The Author(s). Source

Xue S.,CSIRO | Xue S.,Anhui University of Science and Technology | Xue S.,Taiyuan University of Science and Technology | Yuan L.,National Engineering Research Center for Coal Mine Gas Control | And 2 more authors.
International Journal of Mining Science and Technology | Year: 2014

The sudden and violent nature of coal and gas outbursts continues to pose a serious threat to coal mine safety in China. One of the key issues is to predict the occurrence of outbursts. Current methods that are used for predicting the outbursts in China are considered to be inadequate, inappropriate or impractical in some seam conditions. In recent years, Huainan Mining Industry Group (Huainan) in China and the Commonwealth Scientific and Industrial Research Organisation (CSIRO) in Australia have been jointly developing technology based on gas content in coal seams to predict the occurrence of outbursts in Huainan. Significant progresses in the technology development have been made, including the development of a more rapid and accurate system in determining gas content in coal seams, the invention of a sampling-while- drilling unit for fast and pointed coal sampling, and the coupling of DEM and LBM codes for advanced numerical simulation of outburst initiation and propagation. These advances are described in this paper. © 2014 Published by Elsevier B.V. on behalf of China University of Mining & Technology. Source

Qin Z.,CSIRO | Yuan L.,National Engineering Research Center for Coal Mine Gas Control | Guo H.,CSIRO | Qu Q.,CSIRO
International Journal of Coal Geology | Year: 2015

To reduce methane emissions into the workings of a longwall panel, the mechanisms of gas emissions and migration within the longwall goaf must first be understood. Additionally, high performance drainage boreholes must be designed. Many variables affect the goaf gas flow and borehole drainage efficiency, namely the gas release characteristics of gas sources, the heights of caved and fractured zones of the goaf, the location of the drainage borehole and the position of the effective drainage section (the portion of the perforated case and the uncased open hole). This paper illustrates how these variables influence the goaf gas flow patterns and borehole performances through CFD simulations. A permeability model and a gas release curve, which reflect observations from experiments, geomechanical modellings, mine site monitoring and borehole drainage data, were constructed for the mining-disturbed strata and incorporated into the CFD model. The CFD model was calibrated with the actual drainage data from the surface boreholes at a coal mine. Simulation results show that the gas drainage velocities around the perimeter of the panel goaf are higher than in the central goaf, which is consistent with the overlying annular fracture zone model established from CSIRO previous research. Boreholes located within the annular area drew methane at a higher flow rate than those located in the central area, leading to a significant reduction of methane emissions to the ventilation system. Goaf geometry with higher caved and fractured zones has lower pressure and methane concentration but higher gas flow velocity. The location of the effective drainage section of the borehole has significant influence on drainage performance. Boreholes with the bottom end located in the lower region of the fractured zone, (20 m above the roof), can draw more methane than those located in the upper region of the fractured zone (70. m above the roof) and those located in the caved zone (2 m above the roof). © 2015. Source

Yuan L.,National Engineering Research Center for Coal Mine Gas Control | Guo H.,CSIRO | Shen B.-T.,CSIRO | Qu Q.-D.,CSIRO | Xue J.-H.,National Engineering Research Center for Coal Mine Gas Control
Meitan Xuebao/Journal of the China Coal Society | Year: 2011

Presented key results from a recent comprehensive research programme based on integrated field monitoring of mining induced overburden displacement, stress and pore pressure changes at the longwall panel 1115 (1) of the Guqiao Coal Mine, and coupled modelling of strata and fluid behaviours using COSFLOW software, and gas flow simulations at the longwall panel with CFD software. Studied and got the complex dynamics of the interaction between mining induced strata stress changes, fractures, gas flow patterns. The results show that effective range of abutment pressure by mining can reach near 300 m, the range of overburden strata movement and mining-induced fractures area is within 170 m after working face, and beyond the range the fractures are generally compacted, development height for mining-induced fractures of overburden rock and the height of crack zone with flowing pressure dropping remarkablely both can reach 145 m. Based on these, methane drainage scope with high efficiency in overlying coal seam group of working face 1115(1) were obtained, and a new concept that a circular overlying zone existed at the longwall panel for efficient methane capture, and a practical method that helped define the geometry and boundary of this zone. The outputs of the research programme provide a unique methodology and a set of engineering priciples of planning for optimal co-extraction of coal and methane. Source

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