Abstract
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Based on the high gassy and low permeability coal seams geo鄄conditions and developing technology in Tiefa
coalfield,the features of mining鄄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(Compu鄄
tational Fluid Dynamics) numerical modeling. The results show that mining鄄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.