【摘要】 以锦屏一级水电站左岸坝肩边坡微震监测数据为基础,研究蓄水期微震活动性规律,利用S变换(ST)对波形进行分解,并将其应用于左岸坝肩边坡蓄水期与施工期的微震波形处理,以研究其岩石微破裂信号的时频特性。研究表明,(1)微震活动性与地质构造及蓄水活动密切相关,与施工期相比,蓄水期坝肩边坡岩体趋于稳定状态;(2)S变换综合了短时傅里叶变换(STFT)与小波变换(WT)的优点,其在微震等非平稳信号的时频分析中具有独特的优势;(3)时频特性与波形特征相比更加稳定,基于S变换的微震波形分解能较好的揭示波形中包含的震源破坏信息;(4)与施工期相比,左岸坝肩边坡岩石微破裂信号在蓄水期频率升高,持续时间减小,单震型微震事件比例增大,主要是由于在蓄水期左岸坝肩边坡岩体整体性和强度提高,岩体趋于稳定,从而使微震信号表现出不同的时频特征。微震时频参数可以反映岩体的内部微破裂信息,并为其稳定性分析提供参考。更多还原

【Abstract】 Based on the microseismic monitoring data at the left bank abutment slope of Jinping first stage hydropower station, the microseismic activity characteristic is analyzed. The S transform(ST) is used to decompose waveform, and this method is also applied to process the waveforms in the impoundment and construction periods of the left bank abutment slope to investigate the time-frequency characteristics of microfractures. The results show that:(1) Compared to the construction period, the rock mass of the abutment slope tends to be stable in the impoundment period, and the microseismicity is intimately related with the impoundment and geological structures.(2) The ST concentrate the advantages of short-time Fourier transform(STFT) and wavelet transform(WT), it has desirable characteristics in the time-frequency analysis of non-stationary signal.(3) The time-frequency characteristics are more stable than waveform characteristics; and the waveform decomposition based on ST can successfully reveal the damage information of seismic source location in the waveform.(4) Compared to the construction period, the frequency and mono-vibration proportion of microcracking signals of the left bank abutment slope in the impoundment period increases; and the duration decreases. These phenomena are due to the enhancement of rock mass integrity and strength at the left bank abutment slope during the impoundment period. Thus the microseismic signal shows different time-frequency characteristics. The time-frequency parameters of microseismic event can reflect the microfracturing information of rock mass and provide references for the stability evaluation.更多还原