浅埋大跨隧道施工爆破监测与减震技术

以沪-蓉线庙垭分岔隧道工程为背景,研究了其浅埋大跨段掘进爆破的地表震动效应及大断面开挖减震控制技术,并结合爆破监测数据的回归分析,确立了地震波垂向衰减规律的数学模型.综合分析地表及洞内地震波的震动特性发现,地表质点振动主振频率主要集中在低频段;由于表土的滤波作用,主振频率随距离的增加而减小的趋势并不明显;洞内混凝土衬砌减弱了爆破对围岩的冲击,高频地震波衰减极快;开挖区上部的地表振速通常大于未开挖区的振速,浅埋大跨隧道爆破安全控制应以已开挖区顶部的地表振速为准.

Monitoring blasting excavation of shallow-buried large-span tunnel and vibration reduction technology

Based on the engineering background of the Miaoya forked tunnel, the study of vibration characteristic of the ground at the large-span shallow part and blasting vibration reduction technology for large-span excavation has been done, according to the regression analysis for the results of monitoring on blasting vibration, the mathematical model for vertical propagation of blasting vibration has been established. Some conclusions are obtained by analyzing the vibration characteristic of the ground and the tunnel, the dominating vibration frequency at surface mass point mostly focuses on low frequency, the decreasing tendency of dominating vibration frequency at surface mass point is not obvious when distance increases, because some blasting earthquake waves are absorbed by the earth surface covered with soil of certain thickness; the high frequency is mostly absorbed by the concrete of the tunnel lining, so the blasting vibration impacting on the rock becomes weaker, the ground blasting vibration velocity of the excavation region is higher than that of the rock region; the ground blasting vibration velocity at the top of excavation region should be less than that of blasting security control in the large-span shallow tunnel.