动力扰动作用下含水煤样破坏及能量耗散机理研究

Rock burst is one of the major disasters influence on coal mine safety production. The formation of rock burst is usually transmitted to the mining space through the source of the shock stress wave, causing burst accident. Coal seam water infusion is one of the commonly methods for the prevention and control of rock burst. However, the stress wave propagation attenuation and the energy dissipation of the water-saturated coal samples are not clear. Therefore, the study of the dynamic process of water-saturated coal samples is a theoretical problem to be solved in the prevention and control of rock burst. The rock burst of coal and rock failure process can be simplified to water-saturated coal samples under the composite function of static and dynamic loading. Based on the static and dynamic loading test system, the propagation attenuation characteristics of stress wave in water-saturated coal samples are studied by means of theoretical analysis and numerical simulation. An analytical model is established for the propagation of stress waves in the fractures of water-saturated coal samples; Based on the water-saturated fissure evolution, a mechanical model of the static and dynamic fracture mechanics model is established; Based on the analysis of the damage characteristics of water-saturated coal samples, the damage constitutive model of water-saturated coal samples under dynamic disturbance is established; To study the transfer law between the stress wave energy and coal samples’ pre stored energy, and to derive the equation for the release and absorption energy of the water-saturated coal samples. The project results will provide theoretical basis for further understanding of the mechanism of rock burst occurrence and precision control.

冲击地压是影响煤矿安全生产的重大灾害之一。冲击地压的形成常以震源冲击应力波的方式通过煤岩介质传递至采掘空间，造成冲击地压事故，煤层注水是冲击地压防治常用方法之一，然而含水煤样对应力波传播衰减和能量耗散的强弱机理尚不清楚，研究含水煤样冲击动力学过程是冲击地压防治亟待解决的理论问题。冲击地压中煤岩失稳破坏可以简化为含水煤样高静载与动载复合作用的过程，项目利用动静组合加载试验系统，采用理论分析、数值模拟手段，探索应力波在含水煤样中传播衰减规律，推导应力波在含水裂隙传播的解析模型；以含水裂隙结构演变为基础，建立含水裂隙的静、动态力学模型；分析含水对煤样裂隙的损伤特征，构建动力扰动作用下含水煤样的损伤本构模型；揭示应力波能量与煤样预储能量之间的传递规律，建立含水煤样释放和吸收的能量方程。项目成果为进一步认识冲击地压发生机理及精准防治提供理论基础。

我国煤炭需求量长期保持较高水平，煤炭开采逐步转向深部。受制于强烈开采扰动、高地应力、高瓦斯、高非均质性、低渗透性等因素的影响，矿井动力灾害，如冲击地压等事故频繁发生。为揭示煤层注水防治冲击地压理论机制，指导防灾措施优化，项目利用自行研制的饱水装置、RMT-150C和改进SHPB系统进行煤样静载、动静组合加载试验，开展不同含水煤样的动态强度、失稳破坏、能量耗散、损伤断裂等特征研究，得到以下主要成果：静载条件下自然状态煤样峰后应力跌落速度较快，饱水煤样峰后应力跌落较为缓慢。一维动静组合加载条件下煤样的动态应力-应变曲线特征与静载差异较大，煤样动态强度随饱水时间增加逐渐降低，但弹性模量少量升高，动态强度与弹性模量高于静载强度及弹性模量；煤样的动态强度呈现先升高后降低的趋势。三维动静组合加载中，轴向静载在煤样弹性范围内其动态强度随轴向静载增加而增加，饱水煤样的动态强度比自然状态煤样有不同程度的增高，与静载、一维动静组合加载结果相反。建立了静载、动静组合加载条件下含水张开翼型裂纹模型；分析了裂隙水压作用下煤样裂隙动态起始、传播与止裂判据，建立了静载、单独动载、动静组合加载条件下含水煤样的抗压强度数学表达式；确定了一维动静组合加载含水煤样损伤变量，建立了含水和动静组合加载条件下煤样的本构模型。一维动静组合加载自然煤样破坏所需时间大于饱水煤样破坏需要时间，煤样破碎颗粒随饱水时间增长而逐渐变小；相同含水试样破坏失稳耗散能量越大，破碎块度越小，分形维数越大。经过三年的研究工作项目组取得了预期的成果：发表学术论文8篇（SCI收录4篇，EI收录3篇）；申请发明专利3项（授权2项）；完成了负责人王文的博士论文撰写。培养指导硕士毕业生3名（2名已毕业，1名于2020年6月份毕业）参加，国际学术会议2次，国内学术会议3次，完成了项目预期的研究目标和任务。