厚硬顶板致灾机理及定向长钻孔水力压裂控制技术.
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| Title: | 厚硬顶板致灾机理及定向长钻孔水力压裂控制技术. |
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| Alternate Title: | Disaster mechanism of thick-hard roof and control technology by hydraulic fracture with directional long borehole. |
| Authors: | 李兆众1 lizhaozhongxj@163.com, 王瑞2,3,4 wangr1015@163.com |
| Source: | Coal Science & Technology (0253-2336). Apr2026, Vol. 54 Issue 4, p159-173. 15p. |
| Subject Terms: | *Hydraulic fracturing, *Longwall mining, *Boreholes, *Hazard mitigation, *Strains & stresses (Mechanics), *Energy dissipation, *Computer simulation |
| Abstract (English): | In response to the main technical challenges faced by coal production enterprises in the long-term prevention and control of dis-asters caused by the thick-hard hanging roof fracturing in longwall mining faces, taking the 8238 fully-mechanized top-caving longwall face as the engineering background, a mechanical model of thick-hard roof was established, and the disaster mechanism and influencing factors of initial and periodic fracture of the thick-hard hanging roof were analyzed. The results show that the total energy released by the fracture of the hard roof is positively correlated with the coal seam mining thickness m, the hard roof thickness h2, and the tensile strength Rt of the hard roof, and negatively correlated with the direct roof thickness h1. The total energy U2, released by the initial fracture of the main roof is more than twice the total energy U2 released by its periodic fracture. Furthermore, a UDEC numerical calculation model was established, and based on its embedded fluid structure coupling analysis module, the damage and failure laws of hard roof caused by different water injection volumes and fracturing point spacing at a water injection pressure of 40 MPa, as well as the collapse laws of the mining site roof before and after hydraulic fracturing (HF), were analyzed to reveal the weakening mechanism of hard roof caused by directional long borehole HF during the mining stress adjustment. Based on the geological conditions and numerical simulation analysis results, the directional long drilling segmented fracturing parameters for the hard roof (fine sandstone) of the 8238 working face are determined as a single point injection volume of 20 m³ and a fracturing point spacing of 15 m. Based on the control concept of the "energy release -structure weakening- stress regulation", the three-dimensional fracturing technology of "directional long bore segmented fracturing layered control" is proposed and applied in field practice. Field monitoring data revealed: maximum convergence of 236 mm at the coal pillar rib of 5238 roadway, 135 mm at the solid coal rib, and 287 mm maximum roof-to-floor convergence. The initial weighting interval decreased from 45 m to 18 m, while the periodic weighting interval showed 35% average reduction compared with non-HF longwall face. This technical solution effectively ensured safe and efficient extraction in fully-mechanized caving faces under thick-hard roof conditions. [ABSTRACT FROM AUTHOR] |
| Abstract (Chinese): | 针对煤炭生产企业长期面临的长壁采场厚硬顶板悬顶破断致灾防控主要技术难题, 以某矿 8238 综放工作面为工程背景, 建立长壁工作面厚硬顶板破断力学模型, 分析了厚硬悬顶初次及周期破断释放能量的主要影响因素及致灾机理。结果表明: 坚硬顶板破断释放的总能量与煤层开采厚度 m 、 坚硬顶板厚度 h2、坚硬顶板抗拉强度 Rt 呈正相关, 与直接顶厚度 h1 呈负相关, 基本顶初次破断释放的总能量 U1 是其周期破断释放总能量U2的 2 倍以上。建立 UDEC 数值计算模型并基于其內嵌的流一固耦合分析模块, 分析了采动应力调整过程中单点注水压力 40MPa 时, 不同注水体积及压裂点间距对坚硬顶板的损伤破坏规律、水力压裂前后采场顶板垮落规律, 揭示定向长钻孔水力压裂坚硬顶板弱化机理。基于生产地质条件及数值模拟分析结果, 综合确定 8238 工作面坚硬顶板 (细砂岩) 定向长钻孔分段压裂参数为: 单点注水体积 20m³, 压裂点间距 15m。基于"能量缓释—结构弱化一应力调控" 的控制思路, 提出了"定向长钻孔一分段压裂-分层控制"立体压裂技术, 并将其应用于现场实践。现场监测表明: 5238 巷煤柱帮最大移近量为 236mm, 实体煤帮最大移近量为 135mm, 顶底板最敛量为 287mm; 工作面初次来压步距由 45m 减小至 18m; 与未压裂工作面相比, 采场周期来压步距平均降低 35%, 该方案有效确保了厚硬顶板下综放工作面安全高效回采。 [ABSTRACT FROM AUTHOR] |
| Database: | Energy & Power Source |
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