小净距隧道全断面扩挖爆破振动影响分析

既有郁山隧道进口平导为有轨运输小断面,考虑增建二线后用于防灾救援及排水,需扩挖以增大断面。通过理论分析、现场验证和最优化等方法,并结合工程地质特征进行测试和分析,提出新郁山隧道平导扩挖控制爆破方案。运用已有爆破临空面优势条件,利用高段位毫秒雷管点火延时分散性、减少单响爆破炸药用量,以充分发挥精确延时错峰减振技术。实践表明,按所制定的隧道扩挖控制爆破方案进行施工,在净距仅5.69 m的条件下Ⅲ级围岩实现了全断面扩挖,爆破振动对围岩和隧道结构产生的影响可控,既有铁路运营安全。

Impact Analysis on Blasting Vibration of the Whole Section Expansion and Excavation for Tunnel with Small Net Distance

The horizontal guide at the entrance of the existing Yushan Tunnel is a small rail transport section.Considering disaster prevention and rescue and drainage after the addition of the second line,it is necessary to expand and increase the section.Through theoretical analysis,field verification and optimization methods,based on the analysis of engineering geological characteristics,the actual situation was tested and analyzed,and then the new Yushan tunnel plane-guided expansion and excavation control blasting was put forward to take advantage of the existing blasting cavitation conditions,select the dispersivity of high segment millisecond detonator ignition delay,reduce the amount of single-sound blasting,and give full play to the technology of accurate delay and staggered peak damping.Practice shows that according to the proposed tunnel expansion and excavation control blasting scheme,the whole section expansion and excavation construction of the tunnel withⅢlevel surrounding rock is realized under the condition of only 5.69 m in the clear distance,the impact of blasting vibration on the surrounding rock and existing tunnel structure can be controlled,and the existing railway operation is safe.