液态二氧化碳相变破岩振动能量分布研究

Vibrational Energy Distribution of Rock Broken by Phase Transition of Liquid Carbon Dioxide

采用Hilbert-Huang变换方法对地铁基坑开挖工程中液态二氧化碳相变破岩时引起的振动信号的频谱特征、能量分布进行了研究。结果表明,液态二氧化碳相变破岩时引起质点振动的频率主要分布于0~100 Hz范围内,能量主要集中于0~20 Hz,且随距离增加能量逐渐向高频带集中分布;一定距离条件下能量分布主频带内的垂向分量能量比例最高,水平径向次之,水平切向最小,平均值占信号总能量的70%以上,且随震源距增加逐步降低并趋于一致;质点瞬时能量起伏与其振动幅值对应,主要作用于0~0.5 s的时间段内。

The spectrum features and energy distribution of vibration signals caused by phase transition of liquid carbon dioxide during the excavation of metro foundation were investigated by using Hilbert-Huang Transform（ HHT）. Results showed that the vibration frequency of rock broken by phase transition of liquid carbon dioxide was mainly in the range of0 ~ 100 Hz and the vibration energy was mainly concentrated in the range of 0 ~ 20 Hz. With the increasing of the distance,the energy was prone to be concentrated in the high frequency band. And within a certain distance,the vertical component in the main energy distribution frequency band took the largest energy proportion,followed by the horizontal radial component and the horizontal tangent component,with an average value accounting for more than 70%of the total energy of the signal. However,the proportion of three direction component gradually turned to be consistent with an increase in the focal length. The instantaneous energy fluctuation of a particle corresponded to its vibration amplitude and brought great impact in the time period of 0 ~ 0. 5 s.