Outburst coal bed hydraulic phase change cracking cross-cut coal uncovering method

Abstract

The invention provides an outburst coal bed hydraulic phase change cracking cross-cut coal uncovering method, which is applicable to high-gas-outburst coal bed cross-cut coal uncovering operation. The minimum normal distance from the cross-cut coal uncovering working face to the coal bed is greater than or equal to 7m position, a plurality of holes are respectively drilled in the coal uncovering region, a conventional capsule hole sealing coal bed water injection technology is adopted for injecting water into the coal bed through the drilled holes, after the water injection completion, a conventional refrigeration freezing technology is adopted for freezing the coal bed around the water injection hole, in the freezing process, free water in the coal bed is gradually converted from the liquid state into the solid state, and the volume of the water expands for 9.1 percent in the phase change process; after the freezing completion, the freezing coal bed absorbs the underground environment head and gradually thaws. After the freezing thawing completion, the water injection hole and a gas extraction pipeline are connected for gas extraction, or the gas extraction drilling is implemented on the coal bed in the phase change cracking region for gas extraction. When the coal bed gas content is less than 8m<3> / t, the gas extraction is stopped, the water is injected into the water injection hole again, the secondary freezing of the coal bed is completed, and then, the coal bed is uncovered according to a conventional coal uncovering method.

Description

technical field [0001] The invention relates to a method for uncovering coal at a Shimen, in particular to a method for uncovering coal at a Shimen that is suitable for hydraulic phase transition fracturing of coal seams with high gas outbursts. technical background [0002] Coal and gas outburst is one of the main disasters that threaten the safety of coal mine production, especially when Shimen exposes the coal seam, the outburst is the strongest and most dangerous. The stress state of the coal and rock in front of the coal mining face in Shimen is prone to sudden changes, and the elastic potential of the rock and coal seam and the large amount of gas energy are released to cause high-strength outbursts. The average strength of coal outburst in Shimen is more than 6 times that of other roadways, and more than 80% of oversized outbursts occur in the process of coal outburst in Shimen. Due to the particularity of the Shimen coal uncovering construction process, the whole pr...

AI Technical Summary

Problems solved by technology

These measures have achieved certain results in the coal outburst prevention work in Shimen, but there are also great limitations. Measures such as hydraulic cutting can effectively relieve the ground stress and gas pressure, but at the same time destroy the integrity of the coal seam, and the coal seam is exposed. The strength of the regional coal seam is reduced; grouting reinforcement can effectively improve the strength of the coal seam, but the cement mortar can only penetrate and diffuse in the cracks. Due to the small opening of the coal seam cracks and the limited diffusion radius of the cement slurry, the strength of the coal seam in the coal seam can only be realized in a small range. Cannot achieve regional reinforcement

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