煤炭学报2012-1079

㊀第38卷第10期煤㊀㊀炭㊀㊀学㊀㊀报

Vol.38㊀No.10㊀㊀2013年

10月

JOURNAL OF CHINA COAL SOCIETY

Oct.㊀

2013㊀

㊀㊀文章编号:0253-9993(2013)10-1728-07

松散层下覆岩裂隙采后闭合效应及重复开采

覆岩破坏预测

王文学1,2,隋旺华1,2,董青红1,2,胡文武3,谷守侠3

(1.中国矿业大学深部岩土力学与地下工程国家重点实验室,江苏徐州㊀221008;2.中国矿业大学资源与地球科学学院,江苏徐州㊀221008;

3.大统矿业有限公司杨庄煤矿,山东兖州㊀272100)

摘㊀要:为研究开采覆岩裂隙发育的时间效应和为残煤复采评价提供依据㊂采用彩色钻孔电视㊁冲洗液漏失量观测㊁岩芯RQD 指标等对厚松散含水层下煤层开采15a 后的覆岩裂隙闭合效应进行了研究㊂结果表明:距煤层顶板较远的岩体裂隙张开度㊁裂隙率均较小且易闭合,距煤层顶板较近的岩体裂隙张开度大㊁裂隙率大且未能闭合,开采15a 后覆岩导水裂隙高度比煤层开采结束时的最大导水裂隙带高度降低了近40%,垮落带高度稍有降低㊂对比分析发现,开采后的覆岩岩块平均强度比开采前降低了约20%,采用Hoek -Brown 经验公式换算得到破碎岩体单轴抗压强度仅为0.237MPa ,破碎岩体抗压强度已小于自重应力值,处于 潜塑 状态㊂因此,残留煤层的重复开采

覆岩破坏高度计算时,覆岩应按软弱岩类型考虑㊂计算表明,杨庄煤矿3号煤层复采厚度2和3m 时,分别留设15.7和18.2m 的防砂安全煤柱即可起到防溃砂作用㊂关键词:覆岩裂隙;闭合效应;重复开采;导水裂隙带;垮落带;溃砂中图分类号:TD823．21㊀㊀㊀文献标志码:A

收稿日期:2012-10-10㊀㊀责任编辑:常㊀琛

㊀㊀基金项目:国家自然科学基金委员会与神华集团有限公司联合资助项目(51174286);国家重点基础研究发展计划(973)资助项目

(2013CB227903)

㊀㊀作者简介:王文学(1985 ),男,江苏徐州人,博士研究生㊂E -mail:wang603698305@㊂通讯作者:隋旺华(1964 ),男,山东临沂人,

教授,博士生导师㊂E -mail:suiwanghua@

Closure effect of mining-induced fractures under sand aquifers and

prediction of overburden failure due to re-mining

WANG Wen-xue 1,2,SUI Wang-hua 1,2,DONG Qing-hong 1,2,HU Wen-wu 3,GU Shou-xia 3

(1.State Key Laboratory for Geomechanics and Deep Underground Engineering ,China University of Mining and Technology ,Xuzhou ㊀221008,China ;2.School of Resources and Geosciences ,China University of Mining and Technology ,Xuzhou ㊀221008,China ;3.Yangzhuang Coal Mine ,Datong Coal Mining Company ,

Yanzhou ㊀272100,China )

Abstract :This paper presented an investigation of closure effect of mining-induced fractures under thick sand aquifers 15years after coal mining by using color borehole television,mud slurry leakage and RQD (Rock Quality Designation)

of cores,for the purpose of understanding the time effect on mining-induced fracture development and providing a basis for the evaluation of abandoned coal seam remining.The results show that the joint openness and fracture porosity in the rockmass far away from the roof of the coal seam are relatively small and easily compressed.The fractures with lar-ger opening in the rock mass near the roof of the coal seam cannot be compressed to close.The height of water flowing fractured zones reduced by nearly 40%after 15years,while the height of caving zone just reduced slightly.The uniaxi-al compressive strengths of overburden after mining reduced by about 20%compared with those before mining;the u-niaxial compressive strength of broken rock mass with potential plastic state was only 0.237MPa calculated with Hoek-Brown empirical rock failure criterion.Therefore,the formulae for soft rock failure should be used to calculate the overburden failure due to re-mining of the residual coal seam.The research also indicates that the height of safety pillars of more than 15.7or 18.2m is required to prevent panels with a re-mining cutting height of 2or 3m of seam