摘要
利用废弃矿井采空区作为储水空间对矿区生态环境和经济发展具有重要作用,但在不同含水率影响下,煤岩体强度会出现一定的弱化,进而影响地下储库的稳定性。以关闭的大台矿井-710 m开采水平3#煤层煤样为研究对象,研究不同含水率煤样巴西劈裂强度弱化程度、劈裂破坏特征和声发射演化规律;借助CT扫描浸水前后煤样孔隙特征,探究其内在影响机制。研究结果表明:干燥煤样圆盘表面的主要裂纹沿劈裂面存在,而饱和煤样的裂纹偏离劈裂面,形成许多不规则的剪切裂纹。随着含水率的增加,圆盘表面劈裂裂隙平整度降低,从干燥到饱和,裂隙分形维数由1.066升高至1.298;煤样抗拉强度随含水率增加呈线性减小,但峰值应变则呈先增大后减小的抛物线变化;煤样声发射累计计数随含水率增加而逐渐减小,破坏阶段低含水率煤样产生张拉为主的拉剪复合裂隙且尺度较大,高含水率煤样产生小尺度张拉裂隙。煤样浸水后原生裂隙扩张,孔隙率提高2.55%,煤样孔隙率升高使煤样损伤发育加速,进而导致在劈裂过程中更易形成贯通裂隙;水的存在弱化了原生裂隙胶结强度,使劈裂裂隙沿强度较小的节理裂隙面扩张,初始劈裂面粗糙度增加。新增裂隙的减小也同样使声发射强度降低。
Using abandoned mine goaf as water storage space plays an important role in the ecological environment and economic development of mining areas.However,under the influence of different moisture content,the strength of coal and rock mass will weaken,which will further affect the stability of underground storage.In this paper,the weakening degree of Brazilian splitting strength,splitting failure characteristics and acoustic emission evolution law of coal samples with different water content are studied.The coal samples were taken from-710 m mining level,3#coal seam of closed Datai Mine.With the help of CT scanning of pore characteristics of coal samples before and after water immersion,the internal influence mechanism is explored.The results show that the main fractures of dry coal samples disc exist along the splitting plane,while the fractures of saturated samples deviates from the splitting plane,resulting in many irregular shear fractures.With the increase of water content,the flatness of the splitting fracture on the samples disc surface decreases.From dry to saturated,the fractal dimension of splitting fracture on the sample increases from 1.066 to 1.298.The tensile strength of coal samples decreases linearly with the increase of moisture content,but the peak strain increases first and then decreases parabolically.The cumulative count of acoustic emission in coal samples decreases gradually with the moisture content increasing.In the failure stage,the coal samples with low moisture content produce tensionshear composite fractures with large scale,while the coal samples with high moisture content produce smallscale tension fractures.With the help of CT scanning,it is found that the main fracture of coal samples expand after water immersion,and the porosity increases by 2.55%.The increase of the porosity of the coal samples accelerates the damage development of the coal samples,which leads to the formation of through fractures more easily in the splitting process.The existence of water weakens the cementation s
作者
张村
王磊
王潇杰
刘金保
崔舒畅
陈见行
ZHANG Cun;WANG Lei;WANG Xiaojie;LIU Jinbao;CUI Shuchang;CHEN Jianhang(Beijing Key Laboratory for Precise Mining of Intergrown Energy and Resources,China University of Mining and Technology-Beijing,Beijing 100083,China;School of Energy and Mining Engineering,China University of Mining and Technology-Beijing,Beijing 100083,China;Engineering Research Center of Green and Intelligent Mining for Thick Coal Seam,Ministry of Education,China University of Mining and Technology-Beijing,Beijing 100083,China)
出处
《采矿与安全工程学报》
EI
CSCD
北大核心
2024年第2期362-371,共10页
Journal of Mining & Safety Engineering
基金
国家重点研发计划项目(2023YFC3012101)
国家自然科学基金项目(52104155)
中国博士后面上基金项目(2023M733778)。
关键词
废弃矿井
含水率
巴西劈裂
抗拉强度
声发射
弱化机制
abandoned mine
moisture content
Brazilian splitting
tensile strength
acoustic emission
weakening mechanism
