Freezing-type stone door cross-measure coal uncovering method based on hydraulic seam cutting

Abstract

A freezing-type rock cross-measure coal uncovering method based on hydraulic seam cutting is suitable for a rock cross-measure coal uncovering operation in a high-gas outburst coal seam. The method includes following steps: (1) constructing a plurality of water injection holes into a coal uncovering operation surface at a position of the coal uncovering operation surface, wherein a minimum normal distance from the coal seam to the position is not less than 7 m; (2) performing hydraulic seam cutting to the water injection holes through a conventional hydraulic seam cutting technology; (3) when the hydraulic seam cutting is finished, connecting the water injection holes to a gas extraction pipe network to perform gas extraction; (4) when the content of gas in the coal seam is less than 8 m<3> / t, stopping the gas extraction; (5) constructing a freezing holes and a temperature measuring hole respectively at the two sides of the water injection holes; (6) sealing the holes through a capsule hole-sealing device; (7) injecting water into the coal seam through the water injection holes and closing valves when the water injection process is finished to enable the water injected into the coal seam to gradually seep into micro cracks in coal; (8) freezing the coal seam around the water injection holes through a conventional freezing technology to enable free water in the micro cracks in the coal seams to gradually convert from liquid phase into solid phase during the freezing process, so that a strength and an anti-impact performance of the coal are increased and an effect of solidification of the coal seam is achieved; and (9) uncovering the coal seam through a conventional coal uncovering method.

Description

technical field [0001] The invention relates to a gas extraction method, in particular to a hydraulic cutting-based frozen stone door coal removal method suitable for gas outburst in high-gas and low-permeability coal seams. 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 is prone to sudden changes, and the elastic potential of the rock and coal seam and the gas energy are released in large quantities, resulting in high-intensity 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 process of exposing the...

AI Technical Summary

Problems solved by technology

These measures have achieved certain results in the work of uncovering coal and preventing outbursts in Shimen, but there are also great limitations. Measures such as hydraulic cutting can effectively relieve ground stress and gas pressure, but at the same time destroy the integrity of the coal body and expose The strength of the coal body in the coal area is reduced; grouting reinforcement can effectively improve the strength of the coal body, but the cement mortar can only permeate and diffuse in the cracks. Due to the small opening of the coal body cracks and the limited diffusion radius of the cement slurry, the coal can only be uncovered in a small range Regional coal strength, unable to achieve regional reinforcement

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