台阶爆破模型试验下破碎岩石抛掷速度规律分析

Analysis of Throwing Velocity Law of Broken Rocks in Bench Blasting Model Experiment

为了研究台阶爆破破碎岩石抛掷速度的主要影响因素与变化规律,采用量纲分析法确定破碎岩石抛掷速度的主要影响因素,并借助高速摄影系统与台阶爆破模型试验研究不同影响因素下破碎岩石抛掷速度的变化规律.结果表明:破碎岩石抛掷速度的主要影响因素为炸药单耗、最小抵抗线与炸药量的关系(W^(3)/Q)和不耦合系数,抛掷速度对炸药单耗最为敏感,W^(3)/Q与不耦合系数次之;高速摄影图像显示,当爆破作用时间为0.5 ms时,台阶自由面岩石出现位移,当爆破作用时间为2.0 ms时,在爆炸应力波作用下,台阶自由面出现裂缝,破碎岩石的运动形态可分为鼓包运动阶段与抛掷运动阶段,二者之间存在明显的过渡阶段;炸药单耗、W^(3)/Q、不耦合系数与抛掷速度间存在明显的非线性关系,抛掷速度随炸药单耗的增加呈指数函数递增,且存在临界炸药单耗使破碎岩石的抛掷速度出现激增,抛掷速度随W^(3)/Q、不耦合系数的增大呈幂函数递减.

In order to study the main influencing factors and variation law of the throwing velocity of broken rocks in bench blasting, the dimensional analysis method is used to determine the main influencing factors of the throwing velocity of broken rocks. The high-speed photography system and bench blasting model experiment are used to study the variation law of the throwing velocity of broken rocks under different influencing factors. The results show that the main influencing factors of the throwing velocity of broken rocks are unit explosive consumption, the relation between minimum resistance line and explosive quantity(W^(3)/Q), and uncoupling coefficient,the most sensitive factor of the throwing velocity is unit explosive consumption,the second factors are W^(3)/Qand uncoupling coefficient.The high-speed photography images show that when the blasting action time is 0.5ms,the rock displacement appears on the bench free surface;when the blasting action time is 2.0ms,under the action of the explosive stress wave,the crack appears on the bench free surface,and the movement form of the broken rocks can be divided into the bulging movement stage and the throwing movement stage,there is an obvious transition stage between the two movement stage.There is an obvious nonlinear relationship among unit explosive consumption,W^(3)/Q,uncoupling coefficient and throwing velocity,the throwing velocity increases in exponential function with the increase of unit explosive consumption,and there is a critical unit explosive consumption to increase sharply the throwing velocity of broken rocks,the throwing velocity decreases in power function with the increase of W^(3)/Qand the decoupling coefficient.