基于柱状药包爆破漏斗试验的爆破参数优化

Optimization of blasting parameters based on cylindrical charge blasting craters test

为解决青岛地铁五四广场站爆破开挖中的岩石根底问题,通过爆破漏斗试验,并结合LS-DYNA动力有限元软件,分别建立不同药包埋深、炮孔间距的爆破模型,研究爆破漏斗的响应特征及损伤状态,确定了爆破参数。结果表明:漏斗体积、漏斗自由面半径随药包埋深的增加分别呈先增大后减小、持续减小的变化趋势;现场岩体应变能系数为2.538,炸药单耗为735 cm^(3)/g;随着药包埋深的增加,底部岩石监测单元压应力峰值基本保持不变,自由面监测单元所受拉、压应力峰值均呈下降趋势,前者衰减速率小于后者;药包埋深增加使得炸药端部作用加强,炮孔底部纵向裂纹发育增强,横向裂纹发育减弱,不利于岩石的粉碎;随着炮孔间距的增大,岩石根底宽度和高度均增大,增大幅值逐渐减小,根底内部损伤逐渐减小;装药量为400 g条件下,柱状药包最佳埋深为53 cm,此时炮孔孔深为73 cm,炮孔间距取值为66 cm,为保证爆破开挖不产生根底,应以此为基础设计炮孔布置。

To solve the problem of toe roots in the blasting excavation of Qingdao Metro Wusi Square Station,the blasting models with different charge depth and blast hole spacing were established through the cylindrical charge blasting craters test and combined with LS-DYNA dynamic finite element software.The response characteristics and damage state of the blasting crater were studied,and the blasting parameters were determined.The results show that with the increase of charge depth,the volume of the crate increases and then decreases,and the radius of the free surface of the crater gradually decreases.The strain energy coefficient of rock mass at the test site is 2.538,and the powder factor is 735 cm^(3)/g.With the increase of charge depth,the peak stress in the rock monitoring unit at the bottom of the blast hole remains the same,while the compressive and tensile stresses in the rock-free surface unit exhibits a decreasing trend,and the decay rate of the peak compressive stress is greater than that of the peak tensile stress.With the increase of charge depth,the internal action of the blasting pressure in the blast hole is strengthened,and the action of the end of the explosive is strengthened by the clamping action of the rock.The longitudinal crack at the bottom of the blast hole is deepened and the development of the transverse crack is weakened,which is not conducive to the crushing of the rock and causes the formation of the toe rock.With the increase of the blast hole spacing,the width and height of the toe root are increasing,the increasing range and the internal damage of the toe rock gradually decrease.Under the condition of 400 g charge,the best burial depth of the columnar package is 53 cm,the hole depth is 73 cm,and the hole spacing is 66 cm.To ensure that the blasting excavation does not produce roots,the layout of the gun hole should be designed on this basis.