【作者】 张玥；

【导师】 房泽法；

【作者基本信息】 武汉理工大学 ， 采矿工程， 2006， 硕士

【摘要】 V形刻槽爆破是指在炮孔孔壁上按爆破开裂方向,切出一定深度的轴向对称V形槽,采用不耦合装药结构进行的一种断裂控制爆破。此项技术具有断裂面平整,对断裂面两侧的岩石损伤小等特点,在控制轮廓面的爆破中如边坡线上的爆破、隧道周边的爆破、荒料开采切割爆破等方面均有良好的表现,是一种很有推广价值的控制爆破技术。因此用先进的动态数值计算软件对成槽炮孔爆破成缝机理重新认识,研究刻槽参数变化和装药参数变化对断裂控制爆破效果的影响,有着重要的理论价值和实际的工程意义。 本文以花岗岩荒料开采中的切割爆破工程实际为研究对象,为分析V形刻槽爆破成缝机理,及爆破参数改变对刻槽爆破效果影响等内容,建立了各向同性脆性材料的多刻槽孔准平面应变模型,以显式动力分析有限元程序ANSYS/LS-DYNA为模拟运算工具,详细计算了在动载作用下槽孔周围及双孔连心线上岩体的动态应力分布与变化规律,并运用断裂力学理论分析刻槽爆破动态成缝机理,探讨爆破参数变化对V形刻槽爆破效果的影响。主要研究成果和结论包括: 槽孔周围岩体内的动态应力场分布和普通圆孔的应力场分布不同。由于V形刻槽孔的存在,沿刻槽双孔连心线上介质内的动应力明显高于非连心线各处,从理论上证明了槽尖处是裂纹的始裂点,槽孔连心线是裂纹的扩展方向,有力的说明了刻槽爆破较普通轮廓爆破有更好的边界控制效果,与V形刻槽爆破的试件试验和现场爆破实际效果相吻合。 应用断裂力学知识计算出所采用花岗岩质炮孔内的动态起裂临界压力,裂纹继续扩展的临界驱动压力,以及裂纹止裂的临界压力,并与软件模拟计算出的各处单元内压进行比较分析,得出了刻槽尖端裂纹的起裂、扩展、止裂条件。 两刻槽孔同时起爆使应力产生叠加效果,两爆心连线中点处的应力值明显高于单孔爆破时同一位置的应力值。 在V形刻槽爆破中,过小的不耦合系数会导致刻槽炮孔孔壁除刻槽尖端的其它位置也出现裂逢,过大的孔距会导致两孔之间无法贯通成逢形成断裂面,此外刻槽深度和刻槽张角也是V形刻槽爆破中非常重要的参数,合理取值,能使爆炸能量更集中地用于刻槽方向的裂纹扩展。更多还原

【Abstract】 V-shaped notch blasting is that cutting slots with certain depth along axis -direction of the hole is determined according to the blast-crazing, and then load uncoupled charge and detonation. As with this technology, it not only can make rock fracture smoothly and slightly damages toward both sides of fracture plane, but also has good performance in the control outline surface blasting, such as, blasting on the slope, blasting around the tunnel outline surface, cut-blasting in row stone mining and so on. It is valued to be popularized as control blasting technology. Therefore, it is very important in theoretic and practical engineering to restudy fracturing mechanism of notch blasting with dynamic computerized simulation software, and study the impact on notch parameter and charging parameter changing to fractured control blasting effect.In this paper, the object of research is incising blasting engineering in granite row stone exploitation. In order to analyze the fracturing mechanism principles of V-shaped notch blasting and the influence of blasting parameter changing to V-shaped notch blasting effect, the elastic-plastic isotropy and multi-notched holes of plane strain model are set up, dynamical finite element analysis software ANSYS/LS-DYNA is applied, dynamic stress distribution and its change rule of rock around notched holes and between two holes is calculated, dynamic fracturing mechanism is studied with fracture mechanics theory, and influence of blasting parameter changing to notch blasting effect is discussed. The main research achievements and conclusions are as follows.The dynamic stress distribution surround the slot holes are different from the common round holes. Due to the V-shaped holes, the dynamic stress at the center of the two holes is obviously greater than other places, this theoretically proved that the initial crack occurs at the tips of slot, the line between the two holes is the crack extending direction, and strongly confirmed that notch blasting has more advantages in the effect of boundary control, and tally with the experimentation and practical blasting.Fracturing mechanics is applied to figuring out the dynamic initial-crack critical pressure, propagation critical pressure and finial-crack critical pressure, all these pressures were compared with the simulated stress inside the elements to get the conditions of initial-crack, propagation and finial-crack.When the two notched holes detonate at the same time, the stress in the middle point of the line, which connects the two holes center is obviously higher than it in same location by a single hole blasting.In V-shape notch blasting, excessive small uncoupling coefficient make other places of the tips of carving groove holes crack. And excessive large hole-distance makes it incapable to perforate between the two holes. Notch depth and notch angles are important parameters, and when the reasonable notch parameter is chosen, explosion energy is more centralized to the crack expanding direction.更多还原