Mechanical control effect of hard tectonic structure on coal seam gas flow
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Abstract:
To analyze the controlling effect of hard tectonic structure to gas flow at the coal seam heading face, two physical mechanical models are established, normal coal seam driving and hard body embedding coal seam driving. Then according to the above two numerical models, it numerically analyzes the stress distribution characteristics, the coal seam permeability change and the gas flow rule at the coal seam heading face by using rock fracture finite element software RFPA 2D-GAS with solid-gas coupling analysis module, and carries on comprehensive comparative analysis. Finally, combining with two ordinary cases from product field, it verifies the conclusion from the numerical simulation that the concentrated stress influences the coal seam permeability and controls the gas flow. The results show that: the concentrated stress at the coal heading face with hard tectonic structure is like a “closed gate”, as it makes the coal seam permeability obviously lower and blocks the normal migration of gas in the vicinity to the freedom space. In order to eliminate the gas abnormal emission threat at the high gassy coal seam heading face, stress and gas relief measures must be taken to rip the “closed gate” and effectively remove the concentrated stress to provide safe releasing channels for the blocked gas.
