DOI: 10.11799/ce202506015
Optimization of borehole parameters for goaf gas extraction under roof cutting gob-side entry retaining
ZHANG Yongjin
NIAN Jun
ZHAO Bo
LYU Xiaobo
DENG Chunsheng
Abstract：In order to determine the optimal layout parameters of the high level borehole in the goaf of the No.2109 working face of Jining Coal Mine,the complete overlying rock movement process under the working face goaf was analyzed,and the gas distribution law under the Y-type ventilation in the goaf was studied.The results show that:The fracture zone has asymmetric development characteristics under the condition of roof cutting gob-side entry retaining,the maximum height of the caving zone and fracture zone on the cut side is 22 m and 82 m,and the maximum height of the caving zone and fracture zone on the uncut side is 20 m and 86 m.Gas is mainly distributed in the depth of the goaf under Y-type ventilation,and the rich area is located in the fracture zone on the side of the uncut roof,and the maximum gas concentration is 42%.The optimum height and spacing of the upper borehole are 70 m and 20 m,respectively.Under this parameter,the maximum gas concentration near the mining face decreases from 1.94%to 0.497%after 160 days of pumping.According to the site conditions of the working face,eight high level boreholes were designed to extract gas from the gob.In the early stage of extraction,the daily extraction volume of boreholes 1 to 8 showed a gradual increase,which was in line with the distribution of gas before extraction.After extraction,the extraction volume of holes 4 to 8 on the uncut roof side was greater than that of holes 1 to 3 on the roof cutting side.
Keywords：roof cutting gob-side entry retainingY-type ventilationhigh drillinggas extractionnumerical simulation
Publication Date：2025-06-30
Online Publishing Date：2025-08-15(First online date of this platform, not the publication date of the document)
Pages：11( 115-125 )