硬岩地层浅埋地铁隧道爆破振动衰减规律分析

Blasting Vibration Attenuation Law Analysis of Shallow Tunnel Built in Hard Rock Stratum

以青岛地铁3号线工程为依托,针对浅埋硬质花岗岩地层,采用现场实测与统计回归方法分析了试验段横通道爆破振动监测数据,较为系统地研究了钻爆法施工条件下地表最大振动速度、最大单响药量、主频分布的相关关系,总结了适应于该地层的振动衰减经验公式,并通过现场实测数据拟合预测出本段爆破施工最大单响药量。主要研究结论如下:隧道爆破过程中竖向振动速度最大,振动速度随传播距离的增加呈指数规律衰减;掏槽眼爆破受围岩夹制作用最强烈,产生的振动最大,分段起爆能很好地控制爆破振动波的能量分布;爆破振动主频多分布于20~70 Hz范围内,与爆心距和药量无明显相关关系,为避免与周围建筑物产生共振,应避免多段雷管同时起爆,并严格控制最大单响药量。

Based on Qingdao metro Line 3 project that was built in shallow buried hard granite stratum,the monitoring data of horizontal channel blasting vibration in test sections are analyzed by using field measurement and statistical regression method.The relationship among the maximum surface vibration velocity,the maximum single shot charge and main frequency distribution under drilling and blasting construction conditions is systematically studied,the empirical formula of vibration attenuation suitable for this stratum is summarized,and the maximum single charge of blasting construction in this section is predicted based on the site measured data fitting.It is concluded that in the process of tunnel blasting,the vertical vibration velocity is the largest,and the vibration velocity decays exponentially with the increase of propagation distance.Due to the strong"clamping"effect of the surrounding rock,the blasting vibration of the cutting hole is the largest,and the energy distribution of the blasting vibration wave can be well controlled by the staged initiation.The main frequency of blasting vibration is mostly distributed in the range of 20~70 Hz,that has no obvious correlation with the distance between blasting center and the charge weight.In order to avoid the resonance with surrounding buildings,the simultaneous initiation of multiple detonators should not be adopted,and the maximum single shot charge quantity should be strictly controlled.