岩石脆性破坏声发射前兆特性及RFPA模拟研究

发布时间：2018-05-09 09:59

本文选题：脆性岩石 + 单轴压缩　；参考：《江西理工大学》2017年硕士论文

【摘要】：具有岩爆倾向性脆性岩石的受压破坏特征及其地压监测技术是矿山深部开采的基础研究问题。论文以变粒岩、花岗岩和石灰岩为研究对象,进行了单轴压缩下岩石脆性破坏声发射试验,分析了不同脆性岩石的强度与变形特征,探究了岩石受载破裂声发射时频特征演化前兆情况,并利用RFPA模拟了三种岩石破裂声发射演化特征,进一步揭示了单轴压缩荷载作用下岩石脆性破坏声发射前兆特性,主要研究内容与成果如下:1、通过变粒岩、花岗岩和石灰岩单轴压缩声发射试验,从岩石强度与变形两个方面对不同脆性岩石单轴抗压强度、弹性模量、剪切模量等岩石力学参数与变形指标进行分析,总结了脆性岩石破坏三种基本形式和单轴压缩下破坏所经历的三个基本阶段。2、在岩石声发射理论基础之上,对变粒岩、花岗岩和石灰岩在单轴压缩荷载作用下破裂声发射参数演化特征进行了具体分析,并找出其在破坏时的前兆特性:在岩石屈服点或峰值应力附近,声发射振铃累计计数会突然增加,其增长速率也会直线上升,声发射活动极其活跃,声发射能量出现激增。3、对单轴压缩荷载作用下变粒岩、花岗岩和石灰岩破裂声发射频谱特征进行了详细分析与研究,找出其演化特征及在岩石破坏时前兆表现:在接近脆性破坏时,岩石声发射信号EMD能量熵下降异常或上升异常;声发射信号的峰值频率多数维持在[43.95~92.77KHz],声发射信号能集频宽总体上呈现出由集中到分散的特点;大多数岩石破坏前,声发射信号峰值频率通常会出现异常降低的现象,而声发射信号能集频宽会出现异常扩大的现象。4、对变粒岩、花岗岩和石灰岩单轴压缩下声发射进行了RFPA模拟研究,结果表明:(1)RFPA能很好地模拟单轴压缩下岩石微元破坏、裂纹扩展以及声发射演化,模拟结果与试验结果有较好吻合;(2)在显裂纹出现前,模拟声发射有异常汇聚现象,并且在破坏时,主要以拉伸型声发射为主;(3)位移矢量在模型破裂位置出现条带混乱,而应力矢量形成的条带网络与裂纹扩展保持一致;(4)模拟声发射累计计数曲线出现异常抬头的时间点晚于模拟荷载曲线出现异常下降的时间点,可作为模型破坏前兆信息。
[Abstract]:The characteristics of compressive failure of brittle rock with rockburst tendency and the monitoring technology of ground pressure are the basic research problems in deep mining. Taking granulite, granite and limestone as research objects, the acoustic emission tests of brittle failure of rock under uniaxial compression are carried out, and the strength and deformation characteristics of different brittle rocks are analyzed. In this paper, the evolution precursor of acoustic emission (AE) time and frequency characteristics of rock failure under uniaxial compression is investigated, and three characteristics of acoustic emission evolution are simulated by RFPA, which further reveal the precursor characteristics of rock brittle failure under uniaxial compression load. The main research contents and results are as follows: 1. Through uniaxial compression acoustic emission test of granulites, granite and limestone, uniaxial compressive strength and elastic modulus of different brittle rocks are studied from two aspects of rock strength and deformation. The mechanical parameters and deformation index of rock such as shear modulus are analyzed, and three basic failure forms of brittle rock and three basic stages of failure under uniaxial compression are summarized. On the basis of acoustic emission theory of rock, granulites are studied. The evolution characteristics of acoustic emission parameters of granite and limestone rupture under uniaxial compression load are analyzed in detail, and their precursor characteristics are found out: near the rock yield point or peak stress. The accumulative counting of acoustic emission ringing bell will suddenly increase, and its growth rate will rise in a straight line. The acoustic emission activity is extremely active, and the acoustic emission energy increases sharply. 3. Under uniaxial compression load, the granulite is changed. The characteristics of acoustic emission spectrum of granite and limestone rupture are analyzed and studied in detail to find out the evolution characteristics and the precursor of rock failure: when the rock is near brittle failure, the EMD energy entropy of rock acoustic emission signal decreases or rises; The peak frequency of acoustic emission signal is maintained at [43.95~92.77KHz], and the frequency width of acoustic emission signal is generally from concentration to dispersion, and the peak frequency of acoustic emission signal usually decreases abnormally before most rocks are destroyed. The acoustic emission signal energy concentration frequency width will increase abnormally. The RFPA simulation of acoustic emission under uniaxial compression of metamorphic rocks, granite and limestone shows that the microelement failure of rocks under uniaxial compression can be well simulated by the RFPA. Crack propagation and acoustic emission evolution. The simulated results are in good agreement with the experimental results. The main displacement vector is tensile acoustic emission (AAE). However, the strip network formed by the stress vector is consistent with the crack growth. 4) the time point when the cumulative counting curve of acoustic emission appears abnormal rise is later than the time point when the simulated load curve appears abnormal decline, which can be used as model damage precursor information.
【学位授予单位】：江西理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TD315

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