时序控制预裂爆破参数优化及应用

针对白鹤滩水电站地下厂房的爆破开挖，为降低爆破对岩体的损伤，采用数值模拟与现场试验研究小孔径时序控制预裂爆破中，后爆孔孔间延期时间及后爆孔孔距对时序控制预裂爆破成缝的影响，从而获取合理的延期时间和最佳的后爆孔孔距。研究结果表明，孔径为42mm的时序控制预裂爆破，先爆孔孔距为35cm时，合理的起爆延期时间为75~100μs；综合考虑炸药爆炸能量利用率和成缝效果，最佳的后爆孔孔距为70cm。科学地采用时序控制预裂爆破不仅可以减小钻孔工作量与炸药用量，还能降低对岩体的损伤，可为地下厂房爆破开挖安全、高效的进行提供一条有效的途径。

Optimization of time sequence controlled pre-splitting blasting parameters and its application

In view of the underground powerhouse excavation work by blasting at the Baihetan Hydropower Station Project,in order to reduce the blasting-involved damage to the rock mass,numerical simulation and field test were carried out to analyze the influence of the initiation delay time and the distance between later detonated holes on the blasting and the cracking with time sequence controlled pre-splitting blasting,and the reasonable delay time and the optimum distance between post-detonated holes were obtained.The results show that when the hole diameter is 42 mm and the distance between the pre-detonated holes is 35 cm,the reasonable initiation delay time is 75～100 μs,and the optimum distance between the post-detonated holes is 70cm,with joint consideration of the blasting energy's utilization ratio and blasting effect.It is found that time sequence controlled pre-splitting blasting,used scientifically,is a safe and efficient method to excavate the rock mass close to the underground powerhouse wall,which can reduce the load of blasting,cut down on the explosives used,and limit the blasting-involved damage to rock mass.