花岗岩单轴压缩下电荷信号时频特征研究

Charge signal time-frequency characteristics of granite under uniaxial compression

为进一步研究花岗岩变形破坏的前兆特征,采用自主研发的电荷感应监测系统,获得了花岗岩变形破坏全过程时-频域信息,并设计数字滤波器降噪。研究结果表明:岩石在变形破坏过程中伴随着电荷信号产生,随着加载速率的增大,能量积聚加快,岩石破裂所需积累能量时间越短,产生高幅值电荷信号越提前,应力调整次数增多,高幅值脉冲数量增多。对信号傅里叶变换并进行频谱分析,发现信号主频分布在0~100 Hz。岩石变形破坏频域特征总体表现为主频幅值在岩石产生应力降时急剧增加,且在岩石完全破坏时主频幅值增幅最大,主频幅值与电荷感应幅值增高具有同步性,可将电荷信号与主频幅值急剧提高作为岩石失稳破坏前兆特征之一。设计了数字滤波器,较好地滤除了工频干扰信号和高频噪声信号,提高了频谱分析准确性。

In order to further study the precursory characteristics of deformation and failure of granite,the time-frequency domain informa⁃tion of the whole process of deformation and failure of granite is obtained by using the self-developed charge induction monitoring system,and the digital filter is designed to reduce the noise.The results show that the charge signal is generated in the process of rock deformation and failure.With the increase of loading rate,the energy accumulation accelerates.The shorter the time of energy accumulation for rock fracture,the earlier the high amplitude charge signal is generated,the more the number of stress adjustments,the higher the number of high amplitude pulse increase.Fourier transform and spectrum analysis of the signal show that the main frequency of the signal is in the range of 0~100 Hz.The frequency domain characteristics of rock deformation and failure generally show that the amplitude of the main frequency increases sharply when the stress drop occurs,and the amplitude of the main frequency increases most when the rock is completely de⁃stroyed.The increase of the amplitude of the main frequency and the amplitude of charge induction is synchronous.The sharp increase of the amplitude of the charge signal and the main frequency can be regarded as one of the precursors of rock instability and failure.A digital filter is designed to filter power frequency interference signal and high frequency noise signal,that could improves the accuracy of spectrum analysis.