局部压载破裂闪长岩激发电流变化特征与机理分析  

Characteristics and mechanisms of pressure stimulated rock current in diorite samples locally compressed to failure

作　　者：徐友友 吴立新[1,2] 毛文飞 孙立成 卢菁琛 XU YouYou;WU LiXin;MAO WenFei;SUN LiCheng;LU JingChen(School of Geoscience and Info-Physics,Central South University,Changsha 410083,China;Laboratory of Geohazard Perception,Cognition and Prediction,Central South University,Changsha 410083,China)

机构地区：[1]中南大学地球科学与信息物理学院,长沙410083 [2]中南大学地灾感知认知预知实验室,长沙410083

出　　处：《地球物理学报》2025年第3期1004-1016,共13页Chinese Journal of Geophysics

基　　金：国家自然科学基金项目(41930108,42101394);湖南省自然科学基金项目(2021JJ40725)资助。

摘　　要：岩石受力激发电流(PSRC)与岩石微破裂的形成和发育有关,其变化特征与机理是岩石破裂观测与岩体灾变研究的基础.但是,岩石局部加载破裂过程中的PSRC变化研究欠缺.本文以矿物晶体及粒度相对均匀的地壳典型火成岩-闪长岩为例,制作方柱-锥体闪长岩试件,采用高精度电流测量仪与声发射探测仪,同步观测岩石试件单轴局部压载至破裂过程中受压端与非受压端之间的PSRC变化,并与声发射信号进行比对分析,探究其与应力、微破裂发育的内在联系.实验揭示了闪长岩PSRC变化的阶段性特征,即前期呈低值稳定波动,达峰值应力约86.5%时PSRC出现台阶式上升,幅值为nA级;在峰值应力前1 s内出现幅值达100 nA的急剧振荡式脉冲,并持续波动至岩石破裂失稳.分析认为:闪长岩PSRC的两次显著性变化受加载应力水平、矿物晶体/颗粒强度及微破裂发育进程协同控制,导致岩石体积膨胀点之后不同强度的矿物晶体位错丛集与正空穴电荷激活雪崩,形成两次PSRC叠加效应.本研究对于工程岩体破裂监测、区域地应力场变化监测分析及地震短临监测预测有重要意义.Pressure stimulated rock current(PSRC)is related to the micro-fracturing of rock volume,and its variation characteristics as well as mechanisms are the basis for the observation of rock failure and geo-hazards.However,there are less studies on the variation characteristics of PSRC from rock samples locally compressed to failure.Diorite,as a typical igneous rock of earth crust with relatively uniform mineral particle sizes,was selected to produce particular rock samples with cubic-and-conical shape.The PSRC between the loaded cubic part and the unloaded conical part and the acoustic emission(AE)signals were investigated to discriminate the intrinsic relationship by uniaxially compressing only the cubic part of the sample.The experiments revealed the typical features of PSRC with stagedvariation.The PSRC showed a relative stable fluctuation before the load reaching to 86.5%of peak stress,then a considerable step rising of PSRC appeared with a magnitude of nanoampere.A very sharp oscillation pulse with a magnitude of 100 nA occurred suddenly within 1s before the peak stress and fluctuated continuously until rock failure.It shows that the two significant increments of PSRC might have been controlled synergically by loading stress,mineral crystal/particles strength and micro-fracturing process,which led to the dislocation clustering of mineral crystals/particles of different strength and the massive activation of positive holes,thus made commonly the superposition effects of PSRC.This study is of great significance for monitoring rock mass failure,analyzing to stress field change,and predicting impending tectonic earthquake.

关 键 词：岩石受力激发电流(PSRC) 微破裂 矿物晶体/颗粒 过氧键 应力闭锁 遥感-岩石力学 

分 类 号：P589[天文地球—岩石学]