102
D01;10. 7672/sgjs2013070102
施工技术
CONSTRUCTION TECHNOLOGY
2013年4月上第42卷第7期
小净距地铁隧道爆破动力特性与破坏模式研究
史鹏飞
（中铁十八局集团第一工程有服公司，河北源州072750）
【输要】小净距地铁隧道爆破极易引起先行润衬翻开裂、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。后行润爆破对先行润砌
过大探动破坏。先行洞衬硼迎爆侧边墙衬弱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
现织向拉伸裂纹，先行润衬砌边墙能量密度远大于拱顶。在施工时，应确保爆侧边墙厚度和配筋率。【关键调】隧道工程；爆破；振速；能量特性；破坏模式
中图分类号】TU74;U455.6
【文献标识码］A
[文章编号】1002-8498(2013)07-0102-05
StudyonDynamic Characteristics andFailureModeInducedby
Blasting in Small-distance Tunnels
Shi Pengfei
(The First Engineering Co. , Ld. of China Railwgy 18th Bureau Group Co. , Lad. , Zhuoahou, Hebei 072750, Ching) Abstract: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 μs. 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.
Key words;tunnels; blasting; vibration velocity; energy characteristics; failure mode
由于城市特殊地形条件，采用小净距隧道可以不受地形条件以及总体线路线型的限制，同时小净距隧道穿越各种工程地质，得到了广泛的应用（1-3]。然而后行洞爆破产生的动荷载，极易导致先行洞村砌开裂、剥落等危及结构整体稳定性和行车安全等间题（43)
当今对此方面的研究缺乏系统理论支持，使隧道施工面对此类情况时表现出很大的随意性甚至盲目性，使得实际工程常常表现出两种极端现象：
[作者简介】史需飞，工程师，E-mail；shipengfeimail@163，com
【收稿日期】2012-08-05 万方数据
一是对先行洞进行盲目的爆破，药量过小面无法得到预期进度，造成不必要浪费和施工困难；另一种采用过大的药量爆破，对相邻隧道造成破坏或损坏，给后期的运营带来工程隐患。现行相关规范对小净距隧道修建只是原则性规定，有学者研究了爆破对围岩松动圈的影响；也有学者研究了小净距爆破对运营既有隧道结构振动的影响，或加固中夹岩柱对爆破的减弱效应(*-]。而研究先行洞衬砌振动各向异性及破坏模式等方面并不多。目前学者对小净距隧道研究主要集中在平面数值模拟和经验工程等方面，而对三维爆破引起先行洞村硼动力特