Hydraulic fracturing and grouting solidification combined rock cross-cut coal uncovering method

Abstract

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<2>/4 *L +pir<2>*l*P)*10<-6>, 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.

Description

technical field [0001] The invention relates to a method for uncovering coal at a stone gate, in particular to a rapid coal uncovering method for a stone gate which is suitable for combining hydraulic fracturing and grouting solidification in a soft coal seam with low permeability and strong burst risk. Background technique [0002] In roadway construction in mines with high risk of outbursts, large-scale, high-intensity coal and gas outbursts are most likely to occur when Shimen exposes coal seams, which seriously restricts the safe and efficient production of mines. In the prior art, there are many methods for preventing outburst and uncovering of coal in Shimen, including pre-extracting gas pressure relief method, coal solidification method and so on. All methods necessarily contain the steps of constructing gas drainage holes and gas extraction in front of the stone gate in the roadway excavation process according to the "Coal and Gas Outburst Prevention and Control Regu...

AI Technical Summary

Problems solved by technology

However, during the implementation of the method of uncovering the stone gate, the technologies such as high-pressure water jet slits, hydraulic punching or loosening guns have limited damage to the coal body and the cracks generated within the damage range. The rationality of parameter selection such as the degree of coal seam grouting and the amount of coal seam grouting is the key element to ensure the safety of Jieshimen and improve efficiency, but it is not disclosed in this technical plan. Therefore, the peers need to conduct necessary exploration and experiments in the specific implementation process Accumulation of experience is not convenient for direct promotion and application

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