上行卸压开采顶板裂隙带巷道失稳规律

In order to break through the technical bottleneck of multiple seams ascending destressed mining, and solve the growing maintenance problem of roof roadway, it is of great significance to study on the instability of roof fractured zone roadway. Choosing a typical upward depressurized mining program as research background, theoretical analysis, laboratory experiments, physical simulation, numerical simulation and in-situ tests are applied to explore the law of overlying strata movement, mining induced stress field and mining induced fracture field. Consequently, the process and stable periodic of overlying strata movement and their space-time relationship with face advance are summarized. Also, roof strata regionalization, based on mining induced roof roadway stability, is proposed, which could be used to determine layout of roof roadway between upper and lower limits of fractured zone. Moreover, according to roadway surrounding rock failure characteristics of roof fractured zone roadway and elastic- plastic model for the hollow resin anchor body in drawing loading, anchorage failure and roof fractured zone roadway instability are revealed, while stability conditions and criteria of surrounding rock support structure are obtained.In conclusion, surrounding rock control mechanism and countermeasure for roof fractured zone roadway are put forward, these provide technical support to implementing ascending destressed mining and simultaneous extraction of coal and gas for deep coal resources in China.

为突破上行卸压开采的技术瓶颈，解决上行卸压开采顶板裂隙带巷道日益突出的维护难题，开展顶板裂隙巷道失稳规律的研究具有重大意义。以典型的上行卸压开采为工程背景，采用理论分析、实验室实验、物理模拟、数值分析和原位实测相结合的综合方法研究上行卸压开采采场覆岩运动、应力场及裂隙场，得到卸压开采顶板岩层运动过程、稳定周期，以及采动应力和裂隙的时空演化规律，提出基于顶板采动巷道稳定性的上行卸压开采顶板岩层区划，确定顶板裂隙带巷道布置的上限和下限；进而分析顶板裂隙带巷道破坏特征，并建立空洞树脂锚固体拉拔状态下的弹塑性力学模型，分析顶板裂隙带巷道锚杆锚固失效的规律，揭示上行卸压开采顶板裂隙带巷道围岩破坏及失稳规律，得出上行卸压开采顶板裂隙带巷道支护-围岩结构稳定条件及判别准则，形成上行卸压开采顶板裂隙带采动巷道围岩控制机理与控制对策，为我国深部煤炭资源实施卸压开采、煤与瓦斯共采提供技术支撑。

上行卸压开采配合瓦斯抽采是解决我国高瓦斯低渗透性煤层群瓦斯灾害的关键技术手段，由此产生的顶板裂隙带巷道维护难题和安全问题在煤矿普遍存在，成为制约上行开采推广的瓶颈.. 以典型的上行开采为工程背景，建立了上行开采FLAC数值模拟模型，系统研究了上覆岩层采动应力的动态分布规律及上覆岩层破坏规律，揭示了上覆岩层破坏和应力分布的呈分区性特征。采用物理模拟方法，结合远距离钻孔裂隙窥视、深孔位移监测等多种原位实测手段，跟踪上行开采覆岩裂隙发展及巷道稳定过程，揭示了上行开采上覆岩层裂隙发育过程的时空演化规律，得到了基于采动巷道围岩稳定性的上行开采顶板岩层区划和巷道布置，将覆岩划分5个破坏区，裂隙分为4个区。.采用FLAC数值模拟软件，建立了空洞树脂锚固体数值模拟模型，分析研究了空洞树脂锚杆的力学行为，揭示了树脂锚固体杆体承载特性，并开展了巷道断面形状、侧压系数、围岩岩性以及支护结构等顶板裂隙带巷道稳定性影响因素分析，提出了“等效开挖”和“低效加固区”的概念，给出了顶板巷道应根据λ的大小和主应力方向选择合理断面形状是圆形或椭圆，得到了巷道底鼓是顶板裂隙带巷道最显著的变形特征，合理的底板加固深度为4.0～6.0 m；结合顶板裂隙带巷道变形破坏特征物理模拟研究， 揭示了顶板裂隙带巷道底鼓严重诱发失稳的规律。. 提出了上行开采顶巷道板裂隙带针对性的控制对策，主要包括：选择应力降低的Ⅱ区布置巷道、确定采后165 d为顶板裂隙带巷道开挖时机、优化巷道断面和减小低效加固区、提高围岩强度和支护结构稳定性、以及实现针对性强化控制的合理支护技术，给出了顶板裂隙带巷道稳定性控制关键技术，包括：新型“三高”锚杆强化支护、U型钢支护、多性能无机注浆材料注浆加固技术、底板钻锚注一体化支护等。. 研究成果为我国煤与瓦斯的安全、绿色、高效共采提供了理论和技术指导，进一步丰富和发展采动巷道围岩稳定性控制理论成果。