摘要
巷道掘进效率低是造成煤矿采掘失衡的主要原因,岩巷尤其是大断面硬岩巷道掘进速度慢严重制约煤矿的开拓准备及稳定生产。针对此,提出了以多孔水力压裂技术改造岩体完整性、促进大断面硬岩巷道快速掘进的技术思路。采用PFC颗粒流数值模拟,分析了硬岩巷道掘进工作面水力压裂裂纹扩展规律,探讨了不同地应力、注水压力、压裂孔径、压裂孔间距等压裂参数以及不同注水方式、压裂孔布置形式和岩层组合形式条件下多孔水力压裂缝网耦合扩展规律。结果表明:催生的拉伸、剪切裂缝数量与压裂孔孔径和注水压力呈正相关,拉伸裂缝增长速度显著快于剪切裂缝,水力压裂影响半径约为压裂孔直径的3~5倍。地应力对水力裂缝的扩展起主控作用,压裂裂缝主要沿最大主应力方向延伸;随着σh/σv增大,拉伸裂缝数量和压裂影响半径均减小,且降幅逐渐衰减。固定注水压力压裂方式最先产生裂缝,而固定注水流量产生裂缝较慢,但随着压裂进行,其裂缝的扩展速度比固定注水压力方式快;压裂孔平行阵列式布置比交错式布置更有利于裂缝扩展,裂缝增长速度更快。对比4种典型“软-硬”岩层组合条件下压裂裂缝扩展及裂缝击穿“软-硬”岩层交界面的力学行为发现:压裂裂缝在由较软岩层进入较硬岩层后扩展速度变慢,且延伸长度减小;主裂缝从软岩进入硬岩时易发生偏转,而从硬岩进入软岩时则更易直接击穿交界面;在软岩中易产生短宽型裂缝,在硬岩中易产生细长型裂缝。结合模拟与工程实践,设计了基于水力压裂“非爆”破岩的硬岩巷道快速掘进作业线,并优化了水力压裂工艺参数,为水力压裂预裂坚硬岩石提高破岩和巷道掘进效率提供了理论支撑与技术方案。
The low efficiency in roadway excavation is the primary cause of imbalance between coal min-ing and roadway excavation in coal mines,and slow advancement in large-section hard rock roadways emerges as a major bottleneck restricting mine development preparation and stable production.To address this issue,this study proposed a technical approach that uses multi-borehole hydraulic fracturing to modify the integrity of hard rock and achieve the rapid excavation of large-section hard rock roadways.Using PFC numerical simulation,it analyzed the fracture propagation patterns during hydraulic fracturing at the excavation face of hard rock roadways,and further discussed the coupling propagation of multi-borehole hydraulic fracture networks under different parameters(including in-situ stress,water injection pressure,borehole diameter,and spacing),water injection methods,fracture hole layouts,and rock formation combinations.The results indicate that the number of induced tensile and shear fractures is positively correlated with the borehole diameter and the injection pressure.Tensile fractures grow much faster than shear fractures,and the hydraulic fracturing influence radius is approximately 3-5 times the borehole diameter.The propagation of hydraulic fractures is mainly governed by in-situ stress and tends to follow the direction of the maximum principal stress.As oh/o,increases,both the number of tensile fractures and the hydraulic fracturing influence radius are reduced at progressively decelerating rates.Constant-pressure injection generates fractures earliest.In contrast,constant-flow injection corresponds to slower initial fracture formation but achieves faster subsequent fracture propagation.Parallel hole arrays are conducive to more efficient fracture propagation compared to staggered layouts.By comparatively analyzing the propagation states of hydraulic fractures and the mechanical behaviors of fractures crossing the soft-hard rock interface under four typical combinations of such strata,it was found that the propagation of hydraulic fractures slows down and their extension length decreases after they enter a harder rock stratum from a softer one.The main fractures exhibit different characteristics when crossing the soft-hard rock interface.To be specific,they tend to deflect when passing from soft rock to hard rock,while they are more likely to directly penetrate the interface when passing from hard rock from soft rock.Short and wide fractures tend to occur in softer rock strata,whereas thin fractures are more likely to occur in harder rock strata.Through a combination of simulation and engineering practice,a rapid excavation workflow for hard rock roadways based on hydraulic fracturing"non-explosive"rock breaking was designed,and the technological parameters of hydraulic fracturing were optimized.This study provides both a theoretical foundation and technical approach for enhancing rock breaking efficiency and roadway excavation speed through hydraulic fracturing presplitting of hard rock formations.
作者
梁顺
张渊
落弘业
姚强岭
吴浩
李学华
种照辉
梁耀午
LIANG Shun;ZHANG Yuan;LUO Hongye;YAO Qiangling;WU Hao;LI Xuehua;CHONG Zhaohui;LIANG Yaowu(School of Mines,Key Laboratory of Deep Coal Resource Mining,Ministry of Education,China University of Mining and Technology,Xuzhou,Jiangsu 221116,China)
出处
《采矿与安全工程学报》
北大核心
2025年第4期807-822,共16页
Journal of Mining & Safety Engineering
基金
国家重点研发计划青年科学家项目(2022YFC2905600)
国家自然科学基金项目(52174139)。
关键词
多孔水力压裂
硬岩巷道
快速掘进
颗粒流模拟
裂缝扩展
multi-borehole hydraulic fracturing
hard rock roadway
rapid excavation
particle flow simulation
fracture propagation
