摘要
小净距地铁隧道爆破极易引起先行洞衬砌开裂、剥落现象,具有很大施工风险。以在建青岛地铁小净距隧道为例,建立三维有限元动力模型,研究先行洞衬砌振动速度、应力状态以及能量时程。后行洞爆破对先行洞衬砌迎爆侧边墙影响最大,最大振速达到15mm/s。振速峰值时刻均<5μs,可采用微差爆破控制地震波叠加效应,避免过大振动破坏。先行洞衬砌迎爆侧边墙衬砌混凝土主要呈振动破坏和剪切破坏;拱顶主要为横向拉伸破坏,易出现纵向拉伸裂纹,先行洞衬砌边墙能量密度远大于拱顶。在施工时,应确保迎爆侧边墙厚度和配筋率。
Blasting in small-distance tunnels has very high construction risk because it is very easy to cause cracking and peeling of linings in existing tunnels. Taking Qingdao metro tunnel as an example, three-dimensional numerical simulation was carried out to investigate the dynamic response of linings, such as vibration velocity, stress and energy characteristics. It is found that, blasting in subsequent hole has highest influence to linings of the existing tunnel on the side wall facing the blast, with the peak particle velocity （PPV） reaching 15 mm/s. Time to reach the peak particle velocity is always less than 5 p.s. Therefore, blastings with millisecond time difference can be adopted to control the superposition of seismic waves and avoid excessive vibration damage. The linings on the side wall facing blasting show a failure mode of vibration damage and shear failure. The linings at vault are mainly controlled by transverse tension failure, with longitudinal stretching cracks. The energy density of linings on side walls is much larger that that of the vault. It is recommended that the thickness and reinforcement ratio of the side wall of the existing tunnel facing the blasting should be guaranteed.
出处
《施工技术》
CAS
北大核心
2013年第7期102-106,共5页
Construction Technology
关键词
隧道工程
爆破
振速
能量特性
破坏模式
tunnels
blasting
vibration velocity
energy characteristics
failure mode
