隧道内部爆破振动传播规律与降振技术研究

Research on Blasting Vibration Propagation Law and Vibration Reduction Technology for Tunnel Excavation

目前隧道施工普遍应用矿山法,爆破振动对隧道内围岩、支护结构的影响及其灾害控制一直是热点问题。为研究爆破振动在隧道内部的传播规律,以某软弱围岩隧道为工程背景,分别对错距三台阶齐爆和分爆的振动信号进行现场监测。采用萨道夫斯基公式非线性回归、Fourier变换方法对测试数据进行分析和研究。结果表明:对于隧道同一断面,拱顶具有振动速度大、振动主频高、衰减速度慢的特点;三台阶间采用100 ms延时爆破时,可以实现爆破能量在时空分布上的离散,振动叠加效应明显减弱。设计单孔爆破试验,掏槽区域中间设置试验孔,试验孔与整个爆破网络的延期设置为100 ms获取单孔振动波形,基于线性叠加原理,计算不同延期时间下掏槽爆破合成振动波形来优选微差延期时间。结果表明:孔间延期时间在4~7 ms时,掏槽爆破引起的峰值振速急剧下降,干扰降振的效果明显,延时超过7 ms后,峰值振速无显著差异;掏槽孔延期时间取7 ms时减振效果最佳,将最佳延期时间应用于现场爆破,取得了良好的降振效果。

At present,mining method is widely used in tunnel construction.The influence of blasting vibration on surrounding rock and supporting structure in tunnel and its disaster control are always hot issues.In order to study the propagation law of blasting vibration inside a tunnel,the vibration signals of simultaneous detonation and detonation at three benches were monitored on site based on the engineering background of a tunnel with soft surrounding rock.The nonlinear regression of Sadovski formula and Fourier transform method were used to analyze and study the test data.The results show that for the same section of the tunnel,the vault has the characteristics of large vibration velocity,high vibration frequency and slow attenuation rate.When 100 ms delay blasting is used between the three steps,the blasting energy can be discretely distributed in time and space,and the vibration superposition effect can be significantly weakened.A single hole blasting test was set in the middle of the cut area,and the single hole vibration waveform was obtained by setting the delay between the test hole and the entire blast as 100 ms.Based on the principle of linear superposition,the delay time was optimized by investigating vibration waveforms synthesized by cut blasting.The results show that when the delay time between holes is 4~7 ms,the peak vibration velocity caused by cut blasting decreases sharply,and the effect of interference is obvious.After the delay time exceeds 7 ms,the peak vibration velocity has no significant difference.