为探讨露天爆破下井下靠近地表平洞结构的爆破地震效应特性,通过露天爆破开挖过程中,在井下平洞拱顶和地面沿轨道方向布设测点,采集了大量井下平洞的爆破地震响应信号。采用小波分析和快速傅里叶变换相结合的分析方法,研究露天爆破地震波作用下平洞结构的响应频谱、能量分布特性。结果表明:爆破地震波作用下,近地表井下平洞拱底和拱顶质点在各个方向上的速度响应信号频率较大,主要集中在10～312 Hz;主频所处波段的能量占爆破震动总能量的大部分;平洞结构在铅直方向上的速度响应信号频率要低于水平方向的信号频率,且铅直方向主频随爆心距变化不大,而水平方向变化较明显;平洞结构拱顶铅直方向速度响应信号频率要低于拱底铅直方向的信号频率,拱顶铅直方向爆破振动响应更应引起重视。

In order to discuss the characteristics of blasting vibration response of tunnel structure near ground surface under open-pit mine blasting, we collected a large amount of blasting vibration response signals of the tunnel structure by arranging measuring points on the underground tunnel vault and the ground along the orbit direction. Furthermore, we discuss the distribution characteristics of frequency spectrum and energy of tunnel based on wavelet analysis and fast fourier transform (FFT) algorithm. The results indicate that, 1)frequencies in tunnel the vault and the bottom of tunnel are larger than those in other positions, mainly in the range of 10-312 Hz; 2) the band of the main frequency accounted for large proportion of total energy; 3) the frequencies in vertical direction are lower than those in horizontal direction, and main frequency in vertical direction doesn’t change much with distance, but variation of main frequency in horizontal direction is obvious; 4) as for velocity response of tunnel structure in vertical direction, signal frequency at tunnel vault is lower than that at bottom of the tunnel, which should be paid more attention to.