Hydraulic fracturing and grouting solidification combined rock cross-cut coal uncovering method
2013
The invention discloses a hydraulic fracturing and grouting solidification combined rock cross-cut coal uncovering method which includes that when roadway drivage reaches a 10m coal layer vertical distance, fracturing holes of a coal layer are drilled, the coal layer is subjected to hydraulic fracturing, and the water injection amount reaches the preset value after above 3MPa pressure drop appears in fracturing; a plurality of grouting holes are drilled when the roadway drivage reaches a 5m coal layer vertical distance; coal layer methane gases are extracted through the fracturing holes and the grouting holes; the coal layer is subjected to quantitative grouting through the grouting holes with grouting pressure to be above 15MPa; and roadway drivage is continued after grouting solidification, and rock cross-cut coal uncovering is completed. Single hole grouting amount includes grouting hole grouting amount M1 and coal layer permeation grouting amount M2 and is calculated according to M=M1+M2=rho*eta/K *(pi*D /4 *L +pir *l*P)*10 , wherein rho is a grouting density, eta is a storage coefficient, K is a grouting foaming expansion rate, D is a drilling diameter, L is grouting hole length, r is a penetration radius of slurry in the coal layer, l is length of the grouting holes in the coal layer and p is a coal layer porosity. The hydraulic fracturing and grouting solidification combined rock cross-cut coal uncovering method has the advantages of being capable of fast and safely performing rock cross-cut coal uncovering, avoiding re-handling, and improving social benefit.
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