断层黏滑失稳过程微震与电荷信号时频特征研究  

Experimental study on the microseism and charge signal time-frequency characteristics in the process of fault stick-slip instability

作　　者：赵扬锋[1] 荆刚 樊艺 潘一山[1,2] ZHAO Yangfeng;JING Gang;FAN Yi;PAN Yishan(School of Mechanics and Engineering,Liaoning Technical University,Fuxin,Liaoning 123000,China;Collaborative Innovation Center of Dynamic Disaster,Liaoning Technical University,Fuxin,Liaoning 123000,China)

机构地区：[1]辽宁工程技术大学力学与工程学院,辽宁阜新123000 [2]辽宁工程技术大学动力灾害协同创新中心,辽宁阜新123000

出　　处：《岩石力学与工程学报》2020年第7期1385-1395,共11页Chinese Journal of Rock Mechanics and Engineering

基　　金：国家自然科学基金面上项目(51274114);辽宁省高校创新人才支持计划(LR2019032);国家重点研发计划项目资助(2016YFC0801403)。

摘　　要：采用微震与电荷感应监测系统作为试验的监测手段,利用双轴加载试验系统对粗晶正长花岗岩进行不同断层倾角及侧压下断层模型进行断层摩擦滑动试验,观察和分析不同倾角与侧压下断层黏滑曲线特征和断层黏滑过程微震与电荷信号时域与频域特征。结果表明:(1)斜交断层双轴加载过程中侧压及断层倾角改变使断层面应力状态发生变化,改变了黏滑曲线特征及断层黏滑时摩擦强度。小倾角断层易发生黏滑,黏滑时释放的能量小震级低,而大倾角断层不易发生黏滑,但断层失稳时应力降较大,失稳时释放的能量大震级高。通过分析侧压和断层倾角的变化,可进一步判断断层黏滑失稳的可能性。(2)斜交断层发生黏滑就会产生高幅值的微震与电荷信号,且微震与电荷信号在应力降产生之前产生,微震与电荷信号基本同步产生,黏滑时的应力降与信号强度有较好的对应关系,黏滑时断层处的电荷信号幅值较大。随着断层倾角及侧压变化,电荷信号幅值及能量有显著变化,微震信号幅值及能量基本不变。(3)微震和电荷信号频带范围为0~100 Hz,两者信号主频在10 Hz以内。断层黏滑前微震与电荷信号频率及功率值增大,黏滑后迅速减小。试验结果表明微震与电荷信号频谱特征比信号幅值有更明显的前兆特征,采用希尔伯特–黄时频分析方法分析微震与电荷信号时频特征能更好地识别断层黏滑过程前兆信息。The characteristics of the fault stick-slip curve with different fault dip angles and confining pressure,and the time domain and frequency domain characteristics of microseism and charge induction signals in the process of fault stick-slip are inspected and analyzed by using the microseism and charge induction monitoring system and a large-scale double-axis test machine. The test material is a kind of coarse grained syenogranite. The results show that,in the biaxial loading process of oblique faults,the changes of the fault dip angle and the confining pressure changes the stress state of the fault plane,the characteristics of fault stick-slip curve and the stick-slip friction strength. The fault with a small dip angle is prone to stick slip with a small magnitude of energy release,while the fault with a large dip angle is not prone to stick slip and has a large stress drop when failure occurs. By analyzing the changes of the lateral pressure and the fault dip angle,the possibility of fault stick slip instability can be further judged. The possibility of fault stick-slip instability can be further judged by analyzing the changes of confining pressure and fault dip. High amplitude microseism and charge signals will be generated simultaneously at the moment of every oblique fault stick-slip and before the stress drop. The stress drop of fault stick-slip has a good corresponding relationship with the microseismic and charge signal intensity,and the charge signal amplitude at the fault is larger when the oblique fault is stick slip. With changing the fault dip or the lateral pressure,the amplitude and energy of charge signals have significant changes while microseismic signals almost keep unchanged. The frequency bands of both microseism and charge signals are in the range of 0-100 Hz with a main frequency less than 10 Hz. The frequency and power of microseism and charge signals increase before fault stick-slip and decrease rapidly after fault stick-slip. The test results show that the spectrum characteristics of micr

关 键 词：岩石力学 黏滑 斜交断层 断层倾角 微震 电荷感应 时频特征 

分 类 号：TU45[建筑科学—岩土工程]