The 4th International Symposium on Mine Safety Science and Engineering (ISMSSE2018)

240 / 2018-05-05 18:41:15

Study on the relationship between the change of blasting stress field and the effect of gas drainage in coal-rock media with deep-hole blasting through strata

mining engineering,through strata blasting,layers of coal-rock media,fan-patterned holes,numerical calculation

Gas of Coal Mine & Coal and Gas Outburst > Gas of Coal mine

The deep-hole blasting through strata has important role for outburst prevention in rock cross-cut coal uncovering and some special area. The difficulty of the research is caused by the area blasted in layers of coal-rock media and different burden in fan-patterned holes. Based on lot of mine experiments，a representative blasting theory through layers of coal-rock is studied by three-dimensional numerical simulation method. The numerical calculation models for the blasting through strata are constructed. The effective stresses variations of different locations at different times are acquired；the law that the effective stresses of different draining holes decreases with increase of the distance is analyzed；and distribution of effective stress along axis in the holes is discussed in the coal seams. The calculation results show that：(1) The perforation range of blasting cracks at top and bottom of the draining hole in layers of coal-rock media is up to 1.4 and 1.8 m respectively. (2) The average value of effective stress in bottom of the hole is 73% higher than in top at the same location because of actions of the stress interference and reflection in bottom of the hole. (3) The blasting effect in coal seam in layers of coal-rock media is better than in single coal seam. Under the same condition，the maximum value of the effective stress at top and bottom of the draining hole in the multi-media is 17%–42% and 6%–24% higher than single coal seam. When average values of effective stress is 12 MPa along axis of the hole，the gas draining gross increases 3 times more than when is 7.12 MPa.