Evolution characteristics of water flowing fracture in shallow buried coal seam in water abundance gully valley area
LAI Xingping;QIAO Hao;SHAN Pengfei;WU Longquan;ZHU Haoyu;ZHAO Haozhou;DAI Ziqiang
富水沟谷区域下浅埋煤层赋存条件特殊,采场上覆岩层导水裂隙发育演化特征复杂。为了揭示沟谷区浅埋煤层在回采扰动作用下覆岩裂隙演化规律,以朱家峁煤矿1305-2工作面过沟谷区回采阶段为工程背景,采用理论分析、物理相似模拟、数值模拟与现场效果验证的方法,建立了覆岩裂隙−渗流场概念模型,开展了覆岩结构发育与微震能量演化研究,分析了覆岩变形与塑性破坏分布特征,提出了针对沟谷区下浅埋煤层导水裂隙防治措施,并应用于现场工程实践。结果表明:开采扰动下裂隙−渗流场模型呈“梯台”结构,并依次划分为初渗区域、稳渗区域、紊渗区域3个区域;将所研究矿井的工况数据代入模型结构,计算出各个渗透区域范围,并根据计算结果对矿井的稳渗区域采取注浆措施。工作面回采至沟谷区段,覆岩裂隙域形态呈现“拱形-梯形-复合梯形”的扩展演化特征,裂隙纵向发育高度达到163 m,并与沟谷区地表贯通。随工作面推进,地表裂隙依次经历“滑移-挤压-撕裂”过程;沟谷区域位移云图呈现出滞后开采“高位梯形”破断形态,在沟底处下沉位移最大,达3.47 m。针对开采导致的裂隙大范围扩展贯通,提出在地面进行采动裂缝注浆处理,在工作面上覆岩层进行注浆封堵,实现过沟谷区开采“井上−井下”联合防治,保证安全开采。该研究结果可为浅埋煤层的过沟谷区开采、采动裂隙防治及富水区“保水采煤”提供新的科学依据。
The occurrence conditions of shallow buried coal seams under the water-rich gully region are special, and the development and evolution characteristics of water-conducting fractures in the overlying strata of the stope are complex. In order to reveal the evolution law of overlying rock fracture in shallow buried coal seam under mining disturbance in gully area, taking the mining stage of 1305-2 working face in Zhujiamao Coal Mine as the engineering background, the conceptual model of overlying rock fracture-seepage field was established by means of theoretical analysis, physical similarity simulation, numerical simulation and field effect verification. The development of overlying rock structure and the evolution of microseismic energy were studied, the distribution characteristics of overlying rock deformation and plastic failure were analyzed, and the prevention and control measures of water flowing fracture in shallow buried coal seam under gully area were put forward and applied to field engineering practice. The results show that the fracture-seepage field model under mining disturbance is a ‘terrace’ structure, which is divided into three regions: initial seepage region, stable seepage region and turbulent seepage region. Substituting the working condition data of the studied mine into the model structure, the range of each infiltration area is calculated, and the grouting measures are taken for the stable infiltration area of the mine according to the calculation results. When the working face is mined to the valley section, the shape of the overburden fracture domain presents the expansion and evolution characteristics of “arch-trapezoid-composite trapezoid”. The longitudinal development height of the fracture reaches 163 m and is connected with the surface of the valley area. With the advance of the working face, the surface cracks experience the process of “slip-extrusion-tearing” in turn. The displacement cloud map of the valley area shows a “high trapezoidal” fracture pattern of lagging mining, and the subsidence displacement value at the bottom of the ditch is the largest, reaching 3.47 m. In view of the large-scale expansion and penetration of cracks caused by mining, it is proposed to carry out grouting treatment of mining-induced cracks on the ground and grouting plugging in the overlying strata of the working face, so as to realize the joint prevention and control of “up-hole-down-hole” mining in the gully area and ensure safe mining. The results of this study can provide a new scientific basis for the mining of shallow coal seams in the valley area, the prevention and control of mining-induced cracks, and the “water-preserved coal mining” in water-rich areas.
shallow coal seam;overlying rock fissure;development morphology;fissure treatment;mining in loess gully area
主办单位:煤炭科学研究总院有限公司 中国煤炭学会学术期刊工作委员会