复杂条件下小断面桩井开挖爆破技术

在直径只有 1 2m或 1 5m的深桩井中采用控制爆破进行岩石开挖。通过采用含空孔的直孔掏槽方式、反向起爆 ,并合理选择微差起爆时间 ,桩井爆破的平均炮孔利用率达到了 90 %。针对紧邻桩井的天然气主管线和自来水主管线 ,分别合理确定了安全振速。此外 ,施工中严格控制最大段装药量并进行了爆破震动监测。这些技术措施 ,确保了两条管线的安全。

BLASTING TECHNOLOGY FOR EXCAVATION OF SMALL-SECTIONAL PILE-WALLS IN COMPLEX SURROUNDINGS

The excavation of rock in deep pile-wells with diameters of only 1.2 or 1.5 meters was carried out by use of controlled blasting.Through adopting the parallel cut and inverse initiation,and selecting correct delay-interval,an average blasting efficiency of 90% had been achieved.For the natural gas and tap water pipelines close to the pile-walls,the permitted vibration velocities were determined respectively.In addition,the charge mass of maximum delay-interval was controlled strictly and monitoring of blasting vibration was carried out.These technological measures ensured the safety of two pipelines.