Freezing Shimen Uncovering Coal Method Based on Hydraulic Slit

Abstract

A freezing cross-cut coal cutting method based on hydraulic seam-cutting, comprising: constructing a plurality of water injection holes (5) on a coal cutting working surface (2) at a position where the minimum normal distance between the coal cutting working surface (2) and a coal layer (1) is greater than or equal to 7 m; employing a conventional hydraulic seam-cutting technique to perform hydraulic seam cutting on the water injection holes (5); after finishing the seam cutting, connecting the water injection holes (5) to a gas extraction pipe network and performing gas extraction; when the gas content of the coal layer is less than 8 m3 / t, stopping the extraction; respectively constructing a freezing hole (7) and a temperature measuring hole (6) at two sides of the water injection hole (5); employing a capsule hole sealer (12) to seal a hole; injecting water into the coal layer (1) via the water injection hole (5), and closing a valve after finishing water injection; the water injected into the coal layer gradually seeps into a microfissure of a coal body; and employing a conventional freezing technique to freeze the coal layer around the water injection hole (5), free water in a fissure of the coal layer being gradually converted from a liquid state to a solid state in the freezing process, thereby improving the strength and anti-impact capability of the coal body, solidifying the coal layer, and enabling cutting of the coal layer according to a conventional coal cutting 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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