围岩压力对爆破信号频域能量分布影响研究

Study on the Influence of Confining Pressure on Frequency-Domain Energy Distribution of Blasting Signal

随着金属矿山开采深度进一步加大,上覆岩体引起的高围压极易导致围岩发生片帮冒顶等失稳破坏,目前,所建立的爆破震动效应安全判据均未考虑开挖深度及围岩压力因素。笔者通过对不同围岩压力下巷道围岩的爆破震动效应进行数值模拟,利用小波能量理论在频域范围内分解巷道围岩响应信号,得到响应信号的频带总能量以及在不同频率区间内的能量分布,并得出围岩压力对响应信号频带总能量以及频带能量分布的影响规律。结果表明:围岩压力越大,响应信号的频带总能量越大,且频带总能量的增幅以主频带内能量增幅为主;随着围岩压力增大,次频带内能量向主频带内转移,导致频带能量趋于集中。明确不同围岩压力作用下爆破震动信号频域能量的分布规律,为进一步建立考虑围岩压力因素的爆破震动效应安全判据奠定基础。

With increase of excavation depth, the confining pressure of tunnel is getting higher, which will lead to instability failure of tunnel such as roof fall and collapse, and in the blasting vibration effect safety criterion the excavation depth and confining pressure intensity factor have not been considered. In this paper, the blasting vibration response signal of surrounding rock roof was collected by numerical simulation under different confining pressure. According to the wavelet energy theory, the response signal was decomposed, then the wavelet frequency band energy distribution of different frequency interval was obtained, meanwhile the influence of confining pressure on frequency band total energy and energy distribution was also obtained. The study results show that the bigger the confining pressure intensity, the bigger the frequency band total energy is. The growth of frequency band total energy mainly concentrated in the main frequency band. With the increasing of the confining pressure, the energy of minor frequency bands transferred into main frequency band, which lead to the frequency band energy more focused. Under different surrounding rock pressure, the distribution law of energy in frequency domain of blasting vibration signal is known in order to lay the foundation for safety criterion of blasting vibration effect with considering surrounding rock stress factors.