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Title :Geo-environmental hazards associated with multi-slice longwall mining of the Gondwana Barapukuria coal basin, NW Bangladesh: constraints from numerical simulation
Title alternative :ゴンドワナ・Barapukuria石炭盆地 (北西バングラデシュ)の多層・長壁式採炭に伴う地質学的災害危険分析:数値シミュレーションに基づく評価
Authors :Rafiqul, Islam Md.
Issue Date :Jun-2009
Abstract :This dissertation connects the Boundary Element Method (BEM) and Finite Element Method (EFM) with its practical applications to recognize underground mining related geo-environmental hazards associated with the Gondwana Barapukuria Coal Basin of northwest Bangladesh. .A total of three models are presented to recognize ground movement and water inrush/inflow. The study uses both FEM and BEM numerical analyses to evaluate stress redistribution, strata failure, and water inflow enhancements that result from the coal extraction operations. It is apparent from the fracture heights that large amounts of caving would occur towards the roof due to the multi-slice extraction of coal, and finally would be linked with the water-bearing Dupi Tila Formation. For the case of seam gas outburst, three models are also presented in this study. Model A assumes horseshoe-shaped geometry, model B assumes trapezoid-shaped geometry, and model C assumes horseshoe-shaped geometry coupled with a roof fall-induced cave generated by the break-up of rock materials along the vertical dimension of an igneous dyke. From these simulation results, it is thought that the extension of the dyke-induced perturbation zone toward the roof, floor, and rib sides of the entry roadway initially creates small tensional cracks that gradually grow into large-scale tensional features. These features could also be responsible for high concentrations of gas, which are emitted into the mine from fractured coals due to insufficient mine ventilation and low atmospheric pressure. Mining-induced fault reactivation and its impacts on main conveyor belt roadway have been focused as an adverse geo-hazard for the safe operation of the mine. The simulation results illustrate that the mining-induced redistribution of stresses causes significant deformation within and around the two faults_ Failure trajectories that extend towards the roof and left side of fault indicate that mining-induced reactivation of faults is not sufficient to generate water inflow into the mine. However, if movement of strata occurs along the fault planes due to regional earthquakes, and if the faults intersect the overlying Lower Dupi Tila aquiclude, then liquefaction could occur along the fault zones and enhance water inflow into the mine. Considering all geo-hazards, I recommend for rethinking about coal bed methane (CBM) resource potential rather than underground mining of Barapukuria coal basin.
Type Local :学位論文
Publisher :Rafiqul, Islam Md.
URI :http://hdl.handle.net/20.500.12000/18548
Grant id :18001理工研第172号
Date of granted :2009-09-11
Degree name :博士(学術)
Grantor :琉球大学
Appears in Collections:Doctoral Dissertation (Graduate School of Engineering and Science)

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