掏槽控制爆破中减振空孔的布置形式及参数对隧道爆破效果有着重要的影响.通过分析掏槽爆破减振孔降振机理提出合理的减振孔布置方式,借助光滑粒子流体动力学方法(SPH),定量评价了孔径、孔距和布置方式对监测点平均和最大振速控制的效果,系统分析了空孔对掏槽爆破破岩效果影响,并结合实际工程开展相关验证试验.结果表明:1)岩石掏槽爆破抛掷效果与空孔布置形式和数量之间表现出强相关性,同时SPH得出结果表明减振孔布置方式既能保证爆破破碎效果,还可降低爆破振动效应;2)在实际工程应用中,建议减振孔应采用综合布置方式,尽量增大空孔直径,且减小Ⅱ类空孔孔间距;3)将提出的减振布孔技术应用于实际地铁隧道工程,地表振速精确控在0.15 cm/s以内,隧道掘进爆破炮孔利用率整体提高了 14.2％,成功将循环进尺从0.75 m提升至1.5 m.
Vibration reduction and hole layout technology for subway tunnel cutting blasting
The layout form and parameters of vibration reduction holes in controlled cut blasting have a complex influence on the effect of tunnel blasting.Therefore,firstly,we analyzed the vibration reduction mechanism of the vibration reduction holes for hollowing blasting and proposed a reasonable arrangement of vibration reduction holes,secondly,with the help of slippery particle hydrodynamics(SPH),we quantitatively evaluated the effect of three key factors(hole diameter,hole spacing and arrangement)on the control of average and maximum vibration speed and stress at monitoring points,and systematically analyzed the influence of empty holes on the effect of hollowing blasting to break up the rock,and finally,combined with the actual project to carry out the relevant verification test.Finally,relevant verification tests are carried out in conj unction with the actual project.The results show that:1)The rock blasting throwing effect and throwing speed show a strong correlation with the form and number of empty holes arranged,while the results obtained by SPH verified that the vibration-damping hole laying scheme proposed in this paper can not only ensure the blasting crushing effect,but also reduce the vibration effect of blasting.2)In practical engineering applications,it is recommended that the damping holes should be arranged in a comprehensive manner,the diameter of the empty holes should be increased as much as possible,and the spacing of the type Ⅱ empty holes should be reduced.3)When the proposed vibration damping technology is applied to the actual subway tunnel project,the average surface blasting velocity is controlled within 0.5 cm/s,the overall utilization rate of tunnel blasting holes is increased by 14.2％,and the circulation footage is successfully increased from 0.75m to 1.5 m.
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