In multi-seam mining,the interlayer rock strata between the upper coal seam(UCS)and the lower coal seam(LCS)appear damage and strength weakening after mining the UCS.Ground stability control of the gob-side entry reta...In multi-seam mining,the interlayer rock strata between the upper coal seam(UCS)and the lower coal seam(LCS)appear damage and strength weakening after mining the UCS.Ground stability control of the gob-side entry retaining(GER)under the gob with close distance coal seams(CDCS)is faced with difficulties due to little attention to GER under this condition.This paper focuses on surrounding rock stability control and technical parameters design for GER under the gob with CDCS.The floor rock strata damage characteristics after mining the UCS is first evaluated and the damage factor of the interlayer rock strata below the UCS is also determined.Then,a structural mechanics model of GER surrounding rock is set up to obtain the main design parameters of the side-roadway backfill body(SBB)including the maximum and minimum SBB width calculation formula.The optimal SBB width and the water-to-cement ratio of high water quick-setting material(HWQM)to construct the SBB are determined as 1.2 m and 1.5:1.0,respectively.Finally,engineering trial tests of GER are successfully carried out at#5210 track transportation roadway of Xingwu Colliery.Research results can guide GER design under similar mining and geological conditions.展开更多
To solve the problems appeared in mining process of No.2 seam, the ascending stress-releasing mining method was adopted. Studying on the reasonable layout of actual mining roadway in upper coal seams is the preconditi...To solve the problems appeared in mining process of No.2 seam, the ascending stress-releasing mining method was adopted. Studying on the reasonable layout of actual mining roadway in upper coal seams is the precondition of successful ascending mining. By using ＂device of leak measuring by blocking up double ends＂, it detected the height of overburden water flowing fractured zone originated from sub-coal seams mining. Thus it proved that the actual mining roadway of No.2 upper ascending seam was located in the smooth sagging zone. On the basis of analyzing the stress-releasing effect of sub-coal seams mining to upper coal seams by using RFPA software, it analyzed the stability of up-face coal seams and the reasonable location of starting cut in up-face coal seams. It also analyzed the reasonable gateway location in upper coal seams, which ensured the crossheading in upper coal seams out of the effect of sub-coal work face mining by using theory of underground pressure. Meanwhile, the reasonable pillars dimensions in upper coal seams by building the structure mechanics model of stope were researched. It can make the roadway driven along next goaf to be located in low stress zone, and be beneficial to keeping roads stable owing to less stress of surrounding rock. Finally, it tested the rationality of the layout method of roads in upper coal seams by engineering field measurement in 3221 working face.展开更多
针对中近距离松软低透气性突出煤层群抽采防突难题,以皖北矿区任楼煤矿突出煤层群瓦斯地质条件为工程背景,在对松软煤层水力割缝卸压增透机制、首采层割缝工艺参数等研究的基础上,提出了首采层煤巷条带水力割缝卸压增透、煤层群瓦斯联...针对中近距离松软低透气性突出煤层群抽采防突难题,以皖北矿区任楼煤矿突出煤层群瓦斯地质条件为工程背景,在对松软煤层水力割缝卸压增透机制、首采层割缝工艺参数等研究的基础上,提出了首采层煤巷条带水力割缝卸压增透、煤层群瓦斯联合抽采的综合治理技术,优化了钻孔布置方式,并进行了工程应用。结果表明:割缝实施后钻孔的瓦斯抽采浓度、单孔日均抽采纯量分别是常规钻孔的4.27倍、3.94倍,煤层透气性提高了22~31倍,首采层72号煤层割缝后的防突有效半径可提高至5 m以上,检验抽采半径5 m处的瓦斯含量指标为4.13 m 3/t,在有效解决首采层煤巷条带瓦斯灾害的同时,钻孔工程量降低了2/3以上。展开更多
基金financial support from the National Natural Science Foundation of China(Nos.51804111,51974117,51904102,and 52074117)Natural Science Foundation of Hunan Province(No.2020JJ5194)the Postgraduate Scientific Research Innovation Project of Hunan Province(No.CX20200991)。
文摘In multi-seam mining,the interlayer rock strata between the upper coal seam(UCS)and the lower coal seam(LCS)appear damage and strength weakening after mining the UCS.Ground stability control of the gob-side entry retaining(GER)under the gob with close distance coal seams(CDCS)is faced with difficulties due to little attention to GER under this condition.This paper focuses on surrounding rock stability control and technical parameters design for GER under the gob with CDCS.The floor rock strata damage characteristics after mining the UCS is first evaluated and the damage factor of the interlayer rock strata below the UCS is also determined.Then,a structural mechanics model of GER surrounding rock is set up to obtain the main design parameters of the side-roadway backfill body(SBB)including the maximum and minimum SBB width calculation formula.The optimal SBB width and the water-to-cement ratio of high water quick-setting material(HWQM)to construct the SBB are determined as 1.2 m and 1.5:1.0,respectively.Finally,engineering trial tests of GER are successfully carried out at#5210 track transportation roadway of Xingwu Colliery.Research results can guide GER design under similar mining and geological conditions.
文摘To solve the problems appeared in mining process of No.2 seam, the ascending stress-releasing mining method was adopted. Studying on the reasonable layout of actual mining roadway in upper coal seams is the precondition of successful ascending mining. By using ＂device of leak measuring by blocking up double ends＂, it detected the height of overburden water flowing fractured zone originated from sub-coal seams mining. Thus it proved that the actual mining roadway of No.2 upper ascending seam was located in the smooth sagging zone. On the basis of analyzing the stress-releasing effect of sub-coal seams mining to upper coal seams by using RFPA software, it analyzed the stability of up-face coal seams and the reasonable location of starting cut in up-face coal seams. It also analyzed the reasonable gateway location in upper coal seams, which ensured the crossheading in upper coal seams out of the effect of sub-coal work face mining by using theory of underground pressure. Meanwhile, the reasonable pillars dimensions in upper coal seams by building the structure mechanics model of stope were researched. It can make the roadway driven along next goaf to be located in low stress zone, and be beneficial to keeping roads stable owing to less stress of surrounding rock. Finally, it tested the rationality of the layout method of roads in upper coal seams by engineering field measurement in 3221 working face.
文摘针对中近距离松软低透气性突出煤层群抽采防突难题,以皖北矿区任楼煤矿突出煤层群瓦斯地质条件为工程背景,在对松软煤层水力割缝卸压增透机制、首采层割缝工艺参数等研究的基础上,提出了首采层煤巷条带水力割缝卸压增透、煤层群瓦斯联合抽采的综合治理技术,优化了钻孔布置方式,并进行了工程应用。结果表明:割缝实施后钻孔的瓦斯抽采浓度、单孔日均抽采纯量分别是常规钻孔的4.27倍、3.94倍,煤层透气性提高了22~31倍,首采层72号煤层割缝后的防突有效半径可提高至5 m以上,检验抽采半径5 m处的瓦斯含量指标为4.13 m 3/t,在有效解决首采层煤巷条带瓦斯灾害的同时,钻孔工程量降低了2/3以上。
