无限岩体深孔超前破裂爆破岩体破碎机理及应用基础研究

Hard rock is a big problem for fully mechanized roadway in coal mine, a new safety and effective blasting method is needed for form a large number of fractures in rock mass, satisfy normal work of fully machine, and create no hazard, such as rock throw. This subject take blasting mechanism of deep hole advanced rupture blasting under bi-directional load action as the research object, through high dynamic strain test system, high speed camera system and combined with numerical analysis, research explosion stress wave propagation, stress field distribution and crack propagation characteristics of infinite rock deep hole advanced rupture blasting influence by load pressure, hole diameter, charge structure and coupling coefficient, et al. Disclosure blasting burst mechanism of deep hole advanced rupture blasting in infinite rock. And combined with drilling machines, determine blasting parameters such as hole diameter, hole spacing, charge structure, coupling coefficient, et al. Test acoustic wave velocity, the fracture extension situation and rock strength of before and after blasting by ultrasonic tester, digital camera and other equipments, statistic data of rock size, unit consumption of bit and unit footage time-consuming, establish effect evaluation system of deep hole advance rupture blasting. form a set of theory and technology method of deep hole advance rupture blasting in fully mechanized roadway hard rock section, provides basis for deep hole advance rupture blasting construction in fully mechanized roadway.

坚硬岩石是煤矿岩巷综掘机施工面临的一大难题，寻求一种安全有效的爆破方法使岩体内形成大量裂隙、满足综掘机的正常工作，又不会产生抛掷等危害，成为煤矿综掘巷道硬岩段施工亟待解决的问题。课题以双向加载作用下深孔超前破裂爆破岩体破碎机理为研究对象，通过超动态应变测试系统、高速摄像系统结合数值计算,分析加载压力、炮孔直径、装药结构和不耦合系数等因素对无限岩体内深孔爆破爆炸应力波传播、爆炸应力场分布和裂纹扩展特征的影响，揭示无限岩体深孔超前破裂爆破破岩机理。结合钻孔机具设备，确定炮孔直径、炮孔间距、装药结构、不耦合系数等爆破参数。采用超声波测试仪、钻孔数字摄像仪等仪器，对爆破前后声波波速、裂隙扩展情况以及岩石强度进行测试，结合切割矸石块度、单位截齿消耗量和单位进尺耗时等统计数据，建立深孔超前破裂爆破效果评价体系。形成一套综掘巷道深孔超前破裂爆破的理论与技术方法，为综掘巷道深孔超前破裂爆破施工提供基础。

针对煤矿岩巷硬岩段综掘机施工效率低、截齿消耗大的问题，提出深孔超前破裂爆破增加岩体内裂隙、满足综掘机的正常工作。课题通过模型试验和数值模拟，研究了无限岩体内爆破破岩机理，得到不同双向加载压力时超前破裂爆破岩体内爆炸应力波传播和裂纹扩展规律，分析了炮孔直径、装药结构、加载压力对爆破裂纹扩展的影响。据此设计了大直径深孔超前爆破方案与参数，并进行现场试验研究。提出了综掘巷道硬岩段深孔超前破裂爆破施工工艺，研究了爆破后不同损伤程度岩体及爆生裂纹对截齿切割效果的影响，分析了不同角度爆生裂纹时切割裂纹产生规律。研究结果表明：受深部地层初始地应力影响，岩体中爆炸应力场范围随着初始地应力的增大而减小，岩石爆破难度增加；不同方向初始地应力值存在较大差异时，爆破后最大主应力方向爆炸应力场范围较小，会导致该方向上的裂纹长度也相对较短。爆破参数设计时，应适当减小相邻炮孔的布置间距，同时加强炮孔堵塞，避免“冲孔”泄能、影响爆破效果。爆生裂纹对切割裂纹具有导向作用，随着爆生裂纹倾角的增大至60°时，导向作用逐渐转变为抑制作用，爆生裂纹消耗了截齿的能量、不利于新的裂纹产生。深孔超前致裂爆破应更多地制造垂直于截齿作用点的径向裂纹以提高切割效率。炮孔直径75mm、药柱直径63mm的爆破破裂区为炮孔周围0.424m、损伤范围0.424m~2.3m，爆破振动实测并分析得爆破振动能量集中在50~160 Hz频带范围内，不会对巷道围岩及支护结构造成破坏。