导流隧洞开挖施工的爆破振动监测与分析

Monitoring and analysis of blasting vibration in diversion tunnel excavation

详细分析了导流隧洞地质条件,结合隧洞的布置特点和现场的施工情况,采用固定测点的方案,对隧洞开挖施工进行了现场监测。分析测试数据发现,质点振动速度具有明显的方向效应,质点朝临空面的振动速度明显大于其他方向。测点和爆点不在同一高程时,当两点的高差与爆心距的比值较大时,"高差效应"引起的质点在不同方向的峰值振动速度差别十分明显,当两点的高差与爆心距的比值较小时,"高差效应"明显减弱。对于高差与爆破振动传播和衰减规律之间的关系,以往的研究提出了一些修正公式,但这些公式均把高差作为一个独立的变量进行考虑,物理意义不甚明确。根据前面的数据分析,考虑高差影响的实际意义并结合无量纲分析,取高差与爆心距的比值作为"高差效应"影响因子,对传统爆破振动波衰减经验公式进行了修正,经过对比分析,修正后的爆破振动波衰减规律公式具有更高的精度。同时,对实际监测中出现的振动速度超过安全控制速度的情况进行了分析,及时调整爆破参数,从而有效地控制了爆破振动破坏效应。其研究成果对指导隧道工程开挖爆破施工和保证坝体及大坝帷幕安全起到了重要作用,保证了该工程爆破施工的顺利完成。

Analyzing the geological condition of the diversion tunnel,and according to the layout features of the tunnel and field construction situation,the scheme of fixed measuring points was adopted to monitor the tunnel excavation By analyzing the test data,we found that the particles vibration velocities have obvious directional effect;and the vibration velocities of the particles those faces towards free face are much greater than those of the particles in other direction.If measuring points and explosion points are not in the same elevation,and when the ratio between elevation difference and blast center distance is relatively large,the difference of the peak vibration velocities in different directions caused by elevation effect is obvious;and when the ratio is relatively small,the elevation effect weakens obviously.For the relation between elevation difference and the blasting vibration attenuation,previous studies put forward some amended formulas;however,these formulas took the elevation difference as an independent variable to consider,and the physical meaning was not clear.According to the previous data analysis,considering the practical meaning of elevation effect and combining dimensionless analysis,we take the ratio between elevation difference and blast center distance as the impact factor of elevation effect,and modify the traditional empirical formulas of blasting vibration attenuation.Through contrasting and analyzing,the modified empirical formula is relatively precise.In the meantime,the condition that vibration velocities exceeded the standard is analyzed and blasting parameters are adjusted in time,which control the damage effect of blasting vibration effectively.This research plays an important role in guiding the excavation blasting construction in tunnel projects and assuring the safety of dam body and dam curtain,which ensures the successful completion of blasting construction.