爆破地震波作用下煤岩层共振调控及累积损伤机理

Blasting seismic wave that accounts for a large proportion of the total energy of explosive explosion have not been considered and effectively utilized in coal seam and rock strata blasting weakening, resulting in a smaller blasting weakening scope. The ideas that making the coal seam and rock strata resonate is proposed through regulating the main vibration frequency of blasting seismic wave, for promoting expanding the scope of blasting weakening. Based on the use of electronic detonators for precise time delay, the effect of time delay interval on the blasting seismic wave superposition , attenuation propagation and its main vibration frequency law will be seriously studied through numerical simulation, theoretical research method for determining the time delay interval and blasting seismic wave superposition forecasting model of group hole will be used, thus the regulation mechanism of coal seam and rock strata resonance under blasting seismic will be illustrated. Three dimensional stress vibration load simulation system will be used for true reproduction of blasting seismic, acoustoelectric physical system, NMR and SEM technology will be applied to study the accumulative damage law when coal seam and rock strata resonance occurs, then quantitative evaluation of coal rock resonance effect is obtained. This project is expected to provide a theoretical basis for understanding the resonance regulation mechanism of coal seam and rock strata, effectiveness evaluation and technical measures for improving effectiveness of coal seam and rock strata blasting weakening.

煤岩层爆破弱化过程中，占炸药爆炸能量较大比重的爆破地震波并未得到考虑和有效利用，导致爆破弱化的范围较小。本课题提出对爆破地震波的主振频率进行调控，使其与煤岩层的固有频率一致，以使煤岩层发生共振的思路，以扩大爆破弱化范围。课题采用电子雷管对炸药起爆进行精确延时，采用数值模拟着重研究延时间隔、炸药量、传播距离对爆破地震波的叠加、衰减及其主振频率的影响规律，理论研究延时间隔确定方法及群组炮孔起爆爆破地震波叠加预测模型，进而阐明爆破地震波作用下煤岩层发生共振的调控机制；利用三向应力振动荷载模拟系统对爆破地震波进行真实再现，通过声电物理系统、核磁共振和电镜扫描技术手段研究煤岩层共振时的累积损伤规律，进而获得煤岩层共振效果的定量评价方法。研究成果将为煤岩层的共振调控机制及效果评价提供理论基础，并为提高煤岩层爆破弱化效果提供技术支撑。

在一定的煤矿地质及开采条件下，针对煤矿顶板灾害、冲击矿压、煤与瓦斯突出常见灾害的预防,一般可采取煤岩层爆破弱化方法，以使煤岩层裂纹扩展、强度弱化、应力转移。但是针对这几种灾害的预防，炮孔一般处在三向应力无限介质之中，导致爆破弱化（裂纹扩展）的范围很小。为了扩大爆破弱化范围，本项目提出了基于爆破地震波作用的煤岩层共振调控的思路，即通过对爆破地震波频率进行调控，使其主振频率与煤岩层固有频率相匹配，最终使煤岩层发生共振。本项目理论研究分析了煤岩层固有频率和炮孔延时间隔的确定方法，以及各炮孔产生的爆破地震波子波的叠加模型。通过实验室实验发现，爆破裂纹扩展受地应力的影响非常大，影响爆破裂纹扩展的长度和数目，在大概率上裂纹扩展方向垂直于最小主应力，基于弹性波速，研究了炮孔一定范围内爆破前后的损伤变化；基于损伤分析和上覆岩层破断公式分析，提出煤岩层爆破弱化孔网参数必须与岩层破断规律相结合，并形成了基于预裂爆破原理和爆轰波碰撞原理的岩层分层方法和基于爆破地震波作用下煤层共振调控的瓦斯增透方法。基于爆破地震波作用的煤岩层共振调控的思路，对煤炭开采过程中的灾害防控具有积极意义，对油气、陆域天然气水合物开采也有一定的借鉴意义。