市区地铁车站基坑明挖段爆破开挖工程实践

为了控制复杂环境下车站基坑爆破开挖引起的地震动强度,以重庆市渝北区动步公园地铁车站明挖段基坑爆破开挖工程为背景,研究了车站基坑爆破施工方案。介绍了主爆孔和预裂孔的爆破参数,采用预裂爆破与孔内、孔外延时的立体爆破网路,严格控制单段最大起爆药量为2.16kg和爆破飞石安全距离20m内,并进行了现场爆破振动监测与分析。结果表明,孔内、孔外延时的爆破网路实施基坑爆破开挖,其产生的最大峰值爆破振动速度为0.91 m/s,远小于工程允许的爆破振动速度,爆破地震动强度衰减率达到三分之一。预裂爆破形成的预裂缝将主爆区与被保护对象分隔开,从而有效保护了施工区周边的建筑物。

Blasting and excavation engineering practice of open excavation section of urban subway station foundation pit

In order to control the blasting vibration caused by blasting excavation of subway station foundation pit under complex environment,the blasting and excavation scheme of open excavation section of subway station foundation pit was studied by taking Dongbu Park subway station in Chongqing Yubei district as an example.The parameters of main blasthole and pre-splitting blasthole were introduced.Hole inside and hole outside millisecond-delay blasting network was used.The maximum charge quantity of single delay time was strictly limited within 2.16 kg and the safety distance of flying rock was strictly limited within 20 m.On-site blasting vibration monitoring and analysis were conducted.Blasting vibration results showed that the peak blasting vibration velocity was 0.88 m/s,far less than permissible velocity and the attenuation rate of blasting earthquake intensity reached one third.Pre-spliting crack by pre-spliting blasting separated the main blasting zone from the obj ect to be protected and the buildings around the blasting zone were protected from damage.