定制雷管微差时间实测与识别法在城市隧道爆破设计中的应用

APPLICATION OF MEASURING AND IDENTIFYING DETONATION TIME OF CUSTOMIZED DETONATOR IN BLASTING DESIGN OF URBAN TUNNELS

微差爆破间隔时间的确定,对高安全性振速指标下的城市复杂环境隧道爆破设计具有重要作用。以重庆渝中连接隧道爆破工程为背景,在采用多段定制非电雷管条件下,研究根据爆前、爆后实测雷管延迟时间进行精确爆破设计的方法,用非电雷管实现逐孔掏槽爆破以满足严苛低振速控制要求。比较Hilbert-Huang变换(HHT)理论中用于雷管延迟识别的瞬时能量法与EMD识别法的识别能力,发现EMD识别法识别率为66%~90%,比瞬时能量法高1/3以上。爆后用EMD识别法辨别的延迟时间证明实际爆破微差间隔在爆前样本雷管起爆精度范围之内。为准确控制爆破振动,以识别雷管实际延迟时间和振动波形图为依据调整了爆破参数。现场振动监测数据表明:采用多段位定制非电雷管缓解了雷管段别不足的矛盾,根据实测结合EMD识别法识别获得雷管延迟特性进行爆破设计对于严苛振速控制是可行的,在全程爆破振速不超0.8 cm/s条件下进尺1.8 m,通过2次爆破完成上台阶掘进。这一方法对今后城市密集建筑群下浅埋隧道爆破安全施工具有一定的参考价值。

The accurate determination of the interval between the millisecond blasting plays an important role in the design of tunnel blasting in the complex urban environment under the high safety requirement on blasting vibration. A method of designing accurate blasting based on the firing time of detonators which was measured before blasting and after blasting was proposed for the blasting of a connecting tunnel in Yuzhong,Chongqing.The multi-deck customized non-electric detonators were adopted to meet the strict control requirement of low-vibration in the blasting of single hole cutting. The method of instant energy for identifying the time delay ofdetonators in the Hilbert-Huang transform(HHT) theory was compared with the EMD(empirical mode decomposition) method of identification. The recognition rate of the EMD method of identification was 66% –90%,about one third higher than that of the instant energy method. The detonation time which was identified by the EMD method of identification after blasting proved that the actual millisecond intervals were in the range of accuracy of samples measured before blasting. The blasting parameters were adjusted for accurately controlling the blasting vibration according to the graph of the vibration wave and the actual delayed time. The field data from the vibration monitoring showed that using the multi-deck customized non-electric detonator alleviated the disparity about the lacking of detonator delay. The single hole cutting met the strict requirement of low vibration.The blasting design combined with the measured detonator delay time identified with the EMD method was feasible for strict vibration control. The advance of each blasting reached 1.8 m under the requirement of vibration velocity smaller than 0.8 cm/s and the excavations of upper platform were finished with the blasting twice.