坚硬覆岩预裂弱化改性效应及导水裂缝带控制机理  

Pre-splitting weakening failure characteristics of hard overburden and height control mechanism of water-conducting fracture zone

作　　者：张玉军 李友伟[1] 肖杰 张志巍 李嘉伟 ZHANG Yujun;LI Youwei;XIAO Jie;ZHANG Zhiwei;LI Jiawei(China Coal Research Institute,Beijing 100013,China;Coal Mining and Designing Department,Tiandi Science and Technology Co.,Ltd.,Beijing 100013,China;State Key Laboratory of Coal Mining and Clean Utilization,Beijing 100013,China;CCTEG Coal Mining Research Institute,Beijing 100013,China)

机构地区：[1]中煤科工开采研究院有限公司,北京100013 [2]天地科技股份有限公司开采设计事业部,北京100013 [3]煤炭资源高效开采与洁净利用国家重点实验室,北京100013 [4]煤炭科学研究总院开采研究院,北京100013

出　　处：《煤炭科学技术》2024年第4期105-118,共14页Coal Science and Technology

基　　金：国家自然科学基金面上资助项目(52174079)。

摘　　要：针对深部煤层开采坚硬覆岩条件下导水裂缝带控制问题,充分借鉴坚硬顶板预裂弱化技术,提出预裂弱化坚硬主控覆岩控制导水裂缝带高度的新方法。综合采用实验室试验、理论分析、数值模拟等方法,研究了坚硬主控覆岩预裂弱化改性效应,详细阐述了不同弱化层位对导水裂缝带的控制机理,并进行了实测验证。研究结果表明:预制裂缝可以使坚硬岩石往强度低的方向进行转变,并将完整岩样的劈裂破坏特征转变为以预制裂缝为主控的张拉剪切破坏,坚硬岩石的破坏程度由剧烈趋于缓和;揭示了预制裂缝对坚硬岩体的弱化改性效应,计算得到应力与裂缝耦合的损伤变量,定性的分析了弱化程度与岩性转变的关系,改性后岩体能量存储能力降低,耗散能力增强;数值模拟了不同弱化层位对导水裂缝带的控制效果,综合对比覆岩破坏形态、裂隙数量及破坏高度动态演化规律,发现“马鞍形”破坏形态随着弱化层位的升高而逐渐减弱,覆岩裂隙数量演化基本呈现“缓增−突增”的演化趋势,未弱化以及中、高位弱化覆岩破坏高度动态演化近似呈现“S”形,而中位弱化呈“半抛形”,综合分析得出低位弱化对导水裂缝带的控制效果最好;在分析高、中、低位坚硬岩层破坏特征的基础上,揭示了不同预裂弱化层位控制导水裂缝带发育机理;钻孔实测孟村矿顶板压裂条件下的“两带”发育高度,对比发现预裂弱化条件下裂采比降低,初步验证了顶板预裂弱化对导水裂缝带发育的抑制性。研究成果将为深部矿区耦合灾害防控、水资源及生态保护等领域提供理论和科学依据。In order to address the issue of high development of hard overlying rock water-conducting fracture zones in deep coal mining and achieve water-preserved coal mining by reducing the height of water-conducting fracture zones,a new method is proposed in this study,which combines the techniques of pre-fracturing and weakening of hard main controlling overlying strata.This study comprehensively investigates the modification effect of pre-fracturing and weakening of hard main controlling overlying strata through laboratory experiments,theoretical analysis,and numerical simulation.The control mechanisms of different weakening layers on water-conducting fracture zones are elaborated and validated through field measurements.The results demonstrate that pre-existing fractures can induce the rock mass to shift its failure mode from intact rock fracturing to tension-shear failure controlled by pre-existing fractures,leading to a reduction in the severity of rock mass failure.The weakening effect of pre-existing fractures on the hard rock mass is revealed,and the damage variables coupled with stress and fractures are calculated.The relationship between the degree of weakening and the transformation of rock properties is qualitatively analyzed.It is found that the energy storage capacity of the rock mass is reduced while the dissipation capacity is enhanced after the modification.Numerical simulations are conducted to evaluate the control effect of different weakening layers on waterconducting fracture zones.By comparing the dynamic evolution of overlying rock failure modes,fracture counts,and failure heights,it is observed that the“saddle-shaped”failure mode gradually weakens with the increase of weakening layer height,and the evolution trend of fracture counts follows a pattern of“slow increase-sudden increase”.The dynamic evolution of failure height for unweakened and moderately to highly weakened overlying strata approximately exhibits an“S”shape,while the moderately weakened overlying strata exhibit a“semi-e

关 键 词：坚硬覆岩 预裂弱化 岩层控制 导水裂缝带高度 改性效应 

分 类 号：TD745[矿业工程—矿井通风与安全]