预裂缝减震作用下爆破地震波的频谱特征分析
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摘要
研究在微风化花岗岩石场地深孔爆破地震波通过一条长26 m,深7 m的预裂缝振动传播规律。试验数据分析表明,预裂缝的减震效果与测点与预裂缝的减震效果有关。通过对试验中5个测点处不同测点间的振动强度与比例距离的数据回归分析,预裂缝的减震效果具有一个有效作用范围,在比例距离范围为0.031~0.051 kg1/3/m时,减震效果为15%~30%。试验中预裂缝对爆破地震波的透射率为19%~31%。频谱分析表明,预裂缝对爆破地震波的振动频率具有选择吸收的作用,相当于一个滤波器。经预裂缝作用下的爆破地震波在近测点处具有2个明显主振频带;随着传播距离的增加,地震波的两主振频带信号开始混叠,频带逐渐接近并表现为一个主振动频带。
The propagation law of the blasting seismic waves transmitting through the weakly rotten granite site, where a 26 m in length and 7 m in deep is created by the pre-splitting blasting technique, is studied. The result shows that the damping effect of the pre-split is related with the distance between the pre-split and the point of the seismic wave data collected. By regressing the vibration velocities and the scaled-distance, the formulations show that there exists an effective range that the pre-split weakens the seismic vibration in a large scale. In the range of scaled-distance 0.031~0.051 kg~(1/3)/m, the damping ratio will be in the range of 15%~30%. To the experiment site, the transmission rate of the pre-split to the blasting seismic waves is about 19%~31%. The frequency spectrums show that the pre-split selectively absorbs the blasting seismic signal of the special frequency part. The wave transmitted through the pre-split is mainly composed of two predominating frequency band parts of the signals. With the increase of the distance, the two frequency bands become closer. To some distance, the frequency spectrum of the blasting seismic manifests one frequency band.
The propagation law of the blasting seismic waves transmitting through the weakly rotten granite site, where a 26 m in length and 7 m in deep is created by the pre-splitting blasting technique, is studied. The result shows that the damping effect of the pre-split is related with the distance between the pre-split and the point of the seismic wave data collected. By regressing the vibration velocities and the scaled-distance, the formulations show that there exists an effective range that the pre-split weakens the seismic vibration in a large scale. In the range of scaled-distance 0.031~0.051 kg~(1/3)/m, the damping ratio will be in the range of 15%~30%. To the experiment site, the transmission rate of the pre-split to the blasting seismic waves is about 19%~31%. The frequency spectrums show that the pre-split selectively absorbs the blasting seismic signal of the special frequency part. The wave transmitted through the pre-split is mainly composed of two predominating frequency band parts of the signals. With the increase of the distance, the two frequency bands become closer. To some distance, the frequency spectrum of the blasting seismic manifests one frequency band.
引文
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