下穿隧洞爆破掘进对既有隧洞的振动影响

Vibration Effects on Existing Tunnel Induced by Blasting Excavation of Underpass Tunnel

结合福建晋江隧洞小角度下穿既有上行隧洞的工程施工,采用爆破振动监测和数值模拟方法,研究在建隧洞相对空间变化条件下邻近既有洞的动力响应与振动影响。结果表明:距爆源30 m以内,结构部位和爆心距共同影响振速分布;30 m以外区域,以爆心距影响为主。指出既有隧洞最大振速出现于爆源前方5 m范围内迎爆侧底板高程上,爆源近区的竖直向峰值质点振动速度是控制结构安全的主要监测指标,提出适用于不同监测区域的振速控制值的选取方法。

Based on the construction of Fujian Jinjiang tunnel passing under the upper existing tunnel at a small angle, the dynamic response and vibration effect of adjacent existing tunnel under the conditions of relative spatial variation of newly-built tunnel were studied by using methods of blasting vibration monitoring and numerical simulation. The results show that structural parts and the distance from the explosion source collectively affect the vibration velocity distribution of existing tunnel within 30 m range, meanwhile, the main effect factor changes to the distance from the explosion source outside 30 m range. And the maximum velocity of the existing tunnel occurs at the elevation of tunnel floor facing the blasting side within 5 m ahead of the explosion source, the vertical PPV in the near field of the explosion source is the main monitoring index in the safety control of structure. The method of selecting the con- trol value applied to different monitoring areas is proposed.