粉质粘土台基处理方式对地震台背景噪声影响分析

Impact analysis of different processing methods on background noise of silty clay station base

计算不同频段范围内背景噪声记录的加速度功率谱密度,在不同台基处理方式下,研究粉质粘土层流动地震观测台站的噪声特征,分析噪声抑制效果,发现:在0.1—3 Hz频段,增加台基深度、钢钎固定铁板等方式对噪声影响较小;在3—49.8 Hz高频段,2.5 m深混凝土台基、1.5 m深钢钎固定铁板台基等较0.5 m深混凝土台基噪声降低约2—4 d B,1.5 m深钢钎固定铁板台基噪声水平较优;春季白天噪声水平较冬季高5—14 d B,春季夜间噪声水平低于冬季。

By calculating the acceleration power spectral density in different range of frequency, we could analyze the features of background noise in different silty clay station base and the impact of different processing methods for station base on background noise. We find that while the frequency is in the range of 0.1—3 Hz, the depth and the material of station base have very little effect on background noise, while the frequency is in the range of 3 — 49.8 Hz, the background noise in 2.5 m deep concrete station base and 1.5 m deep steel station base is 2 — 4 dB lower than that of 0.5 m deep concrete station base; background noise of 1.5 m deep steel station base is lower than 2.5 m deep concrete station base; the background noise level of day time in spring is higher than in winter, but that of night time is just the opposite.