特大断面隧道爆破开挖对既有隧道振动影响分析

Analysis on Vibration Influence on Existing Tunnel Imposed by Blasting Excavation of Extra-large Cross-section Tunnel

在分析国内外爆破振动理论的基础上阐述要根据具体的工况,有针对性地引入振动速度、振动时间等多种参数进行分析,且以兰渝线关子岭特大断面隧道爆破为依托,应用数值分析方法,模拟特大断面隧道爆破振动对周边建筑物的影响。研究结果表明:既有隧道仰拱迎爆侧附近应力最大;随着时间的推移,上部既有隧道最大拉应力依次出现在迎爆侧仰拱、拱脚、拱顶及背爆墙等位置,并且其强度经历由弱变强,又由强变弱后逐渐减小消失。根据分析结果提出在特大断面爆破施工中应采取的一系列减振施工技术措施,希望为以后遇到类似特大断面爆破施工提供参考。

It is stated, on basis of analysis on the blasting theories at home and abroad, that parameters, such as vibration velocity and vibration time should be introduced to analyze the influence of blasting on the surrounding structures. In the paper, the influence imposed by the blasting excavation of tunnels with extra-large cross-sections is simulated, with Guanziling tunnel on Lanzhou-Chongqing railway as an example. The study results indicate that the stress on the inverts toward the bla.sting side is the largest ; as time goes on, the maximum tensile stress on the upper existing tunnel occurs at the invert, arch foot and crown toward the blasting and the wall backward the blasting in succession; the strength of the stresses varies from weak to strong, then varies from strong to weak and in the end vanishes gradually. A series of vibration-reducing measures are proposed on basis of the study results. The paper can be served as reference for similar projects in the future.