不规则残采面覆岩破断的动载特征与弱化控制研究

At present, it has been an urgent problem for exhausted mine that how to recycle residual resources safely and efficiently. Most of residual coal having mining values is "isolated island" coal mass with goaf in multiple sides. Influenced by adjacent mining, residual coal shape and size, the fracture of overlying strata has a significant dynamic load effect on the subjacent roadway during mining process, which contributes to the continual occurrence in terms of rib spalling and roof fall. Roadway maintaining has been a critical factor for restricting the safe recycling of residual coal. Thus, the project will mainly carry out the following research contents. (1) By analyzing the change law of distribution characteristics of micro-seismic signal, deriving from multiple residual working faces, with working face advancing, the project will invert the spatial structure characteristics of overlying strata fracture. Taking above study results as calibration standard, the project will establish a similar test model for residual working face in classic conditions (namely, different shape and size of residual working face), and will reveal the fracture characteristics of overlying strata and formation mechanism of dynamic load. (2) It will also be established that a theoretical model for the transmission of dynamic load stress wave in different fracture characteristics (e.g. monolayer, multilayer synchronization and multilayer asynchronous fracture). Meanwhile, the project will establish a function relationship between the appearing strength of roadway dynamic load and the initial dynamic load strength in fracture position. Based on above research results, the project will reveal the attenuation law of dynamic load stress wave in different fracture characteristics. (3) Combined with the above research contents, a numerical analysis model coupling dynamic and static state will be established for studying the dynamic load response characteristics of roadway supporting structure, and then a corresponding weakening control technology will be developed to ensure the safe recycling of residual coal resources.

残煤资源安全高效回收是当前衰老矿井迫切需要解决的问题，但具备开采价值的残煤大部分为多侧采空的孤岛煤体，受周围回采及残煤形状、尺寸等影响，回收过程中覆岩破断对下位巷道的动载作用显著，巷道片、冒事故时有发生，巷道安全维护成为制约残煤安全回收的关键因素。为此，本课题主要开展以下研究：1）分析多个残采工作面微震信号分布特征随工作面推进的变化规律，反演覆岩破断的空间结构特征，并以此为校验标准，建立典型条件下（不同残采面形状、尺寸等）残采面的相似试验模型，揭示覆岩破断特征与动载形成机理。2）建立不同破断特征下（单层、多层同步与多层非同步破断）动载应力波传递理论模型，构建巷道动载显现强度与破断位置初始动载强度之间的函数关系，揭示不同破断特征下动载应力波的传递衰减规律。3）结合上述研究内容，建立动静耦合数值分析模型，研究巷道支护结构的动载响应特征，开发相应的弱化控制技术，为残煤资源安全回收提供技术保障。

工作面坚硬顶板破断引起的动载扰动是煤矿生产中常见的现象，对于布置工作面附近的临空巷道这一现象更为显著，支护结构失效以及巷道局部片、冒事故时有发生。本基金基于坚硬顶板破断及活动特征，对顶板动载产生机理、动载应力波传递衰减规律、围岩及巷道支护的动载响应等内容进行研究，并提出了对应的顶板动载弱化控制技术。具体研究内容如下：.（1）根据典型的坚硬顶板工作面条件，建立了坚硬顶板破断失稳的物理实验模型，获得了坚硬顶板活化运动过程中的声发射规律，分析了动载形成原因及主控岩层的失稳特征；进一步建立了动载作用及传播力学模型，揭示了下方临空巷道围岩的动载强度与顶板破断动载源强度之间的关系；.（2）依据动载应力穿越层间结构面的衰减规律，探究了介质属性（泊松比、密度、弹性模量）、结构面属性（法向刚度、切向刚度）对动载应力穿越层间结构面的衰减作用；依据临空巷道动静载耦合作用数值分析模型，研究了不同静载（埋深）下围岩应力、围岩位移、围岩塑性区的动载扰动强度响应特征，揭示了动作作用下的巷道围岩动载扰动大变形机理；.（3）基于顶板动载形成机制及巷道动载响应规律，开发了顶板致裂弱化动载技术和抗动载支护系统；在残留煤柱工作面进行了工业性试验，采用水压致裂技术弱化坚硬顶板，确定了合理的施工工艺和关键参数，建立了以高强蛇形让压锚杆为核心的抗动载支护系统和相应的设计方法，应用效果良好。