Beijing Key Laboratory for Precise Mining of Intergrown Energy and Resources, China University of Mining andTechnology-Beijing
School of Energy and Mining Engineering, China University ofMining and Technology-Beijing
Engineering Research Center of Green andIntelligent Mining for Thick Coal Seam, Ministry of Education, China University ofMining and Technology-Beijing

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 ecologicalenvironment and economic development of mining areas. However, under the influence of differentmoisture content, the strength of coal and rock mass will weaken, which will further affect the stabilityof underground storage. In this paper, the weakening degree of Brazilian splitting strength, splitting fail-ure characteristics and acoustic emission evolution law of coal samples with different water content arestudied. 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 coalsamples disc exist along the splitting plane, while the fractures of saturated samples deviates from thesplitting plane, resulting in many irregular shear fractures. With the increase of water content, the flat-ness of the splitting fracture on the samples disc surface decreases. From dry to saturated, the fractal di-mension of splitting fracture on the sample increases from 1.066 to 1.298. The tensile strength of coalsamples decreases linearly with the increase of moisture content, but the peak strain increases first andthen decreases parabolically. The cumulative count of acoustic emission in coal samples decreases gradu-ally with the moisture content increasing. In the failure stage, the coal samples with low moisture contentproduce tension-shear composite fractures with large scale, while the coal samples with high moisturecontent produce small-scale tension fractures. With the help of CT scanning, it is found that the mainfracture of coal samples expand after water immersion, and the porosity increases by 2.55% . The in-crease 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 ofwater weakens the cementation strength of the main fracture, and then makes the splitting fractureexpand along the joint fracture surface with less strength. The decrease of new fractures also reduces theintensity of acoustic emission.

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)

1 工程背景
2 试样制备与试验方案
2.1 不同含水率试样制备
2.2 试验装置与方案
3 含水率对煤样抗拉力学特性的影响
3.1 不同含水率煤样应力-位移曲线
3.2 不同含水率煤样抗拉强度
3.3 不同含水率煤样巴西劈裂破坏特征
4 不同含水率煤样声发射特征
4.1 不同含水率煤样累计声发射特征
4.2 不同含水率煤样裂隙发育类型
4.3 不同含水率煤样裂隙发育程度
5 抗拉强度含水率影响机制
6 结 论