Construction method for preventing drilling and hole spraying in drilling construction process of extremely soft coal seam

Abstract

The invention discloses a construction method for preventing drilling and hole spraying in the drilling construction process of an extremely soft coal seam. The construction method comprises the following steps that a plurality of parameters such as peak strength, tensile strength, ground stress and the like of a coal body are measured, and a critical drilling diameter for preventing a hole spraying instability phenomenon of a drilled hole is calculated by utilizing a derived formula; after a first-level drill hole is constructed according to the calculated critical drilling diameter, a curing material is injected into the constructed drill hole, and loose coal around the drill hole is solidified; and after consolidation material is solidified, a second-level drill hole (namely a gas extraction drill hole) is constructed in a consolidated area, and construction of one gas extraction drill hole is completed; meanwhile, the diffusion radius of the curing material can also be calculated, so that the phenomenon of instability phenomenon under the action of gas pressure and the ground stress caused by insufficient thickness of the consolidated area of the curing material can be prevented, and the curing material can be saved; grouting pressure is obtained through simulation of a simulation software, and the situation that personal safety of constructors is endangered due to the fact that the grouting pressure is too large is avoided.

Description

technical field [0001] The invention relates to a construction method for gas drainage drilling, in particular to a construction method for preventing drilling and injection holes during the drilling construction process of extremely soft coal seams. Background technique [0002] According to statistics, more than 95% of my country's high-gas and outburst mines belong to low-permeability coal seams, and the coal quality is soft and the gas content is high. In order to prevent coal and gas outburst accidents during the coal mining process, gas is generally extracted through construction gas drainage boreholes underground to reduce the gas pressure of the coal seam in the area to be mined and ensure the safety of mining at the underground working face. [0003] When drilling in soft coal seams, the stability of the drilling is poor, which affects the drilling rate. Therefore, it is particularly important to study the stability technology of the drilling hole wall to improve th...

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Problems solved by technology

But above-mentioned these prior art, all just considered how to prevent borehole wall from collapsing in the drilling process or afterwards, and when drilling in coal seam construction, because drill bit is disturbed to coal seam, blowout phenomenon very easily takes place, and then endangers The personal safety of the construction personnel will not be able to achieve the purpose of stabilizing the wall of the borehole; therefore, how to prevent the occurrence of spray holes during drilling in extremely soft coal seams, so as to ensure the subsequent stability of the wall of the borehole is an important issue. industry research direction

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