不同应力路径下岩石的声发射特征试验研究

发布时间：2018-03-16 20:13

本文选题：砂岩　切入点：泥岩　出处：《安徽理工大学》2017年硕士论文　论文类型：学位论文

【摘要】：本文通过对信湖矿井底车场的顶板和底板内两组砂岩和泥岩取芯,利用理论分析、实验室单轴压缩试验、和RFPA2D数值模拟的手段,对不同应力路径下砂岩和泥岩在单轴压缩下变形破坏全过程进行声发射研究,通过实验数据得到在加载压缩过程中岩石的AE特征、声发射点的空间演化规律,以此分析岩石的力学性质的变化及其变形、损伤破坏情况、破坏模式的对比,可以对岩石的破坏进行监测预报。论文主要进行以下研究工作:(1)根据不同应力路径下的砂岩和泥岩的单轴加载试验得到,砂岩和泥岩在加载破坏过程中全都经历了初始压密阶段、弹性阶段、塑性阶段和峰后破坏阶段;伴随着岩石单轴抗压强度的增加,岩石弹性模量以及声波的传播速度都增加。(2)对砂岩和泥岩在不同应力路径下损伤破坏过程中声发射特征的差异进行分析,得到了泥岩的AE事件数最大值点与岩石的峰值应力并不重合,砂岩的AE事件数峰值点与岩石的峰值应力重合;砂岩的能量峰值较AE事件数峰值提前,泥岩的AE事件数峰值和能量峰值重合。(3)分析循环加卸载过程中应力变化同声发射事件数得出,砂岩的Kaiser效应特征点出现在峰值应力的21%处,即弹性阶段开始处,泥岩的Kaiser效应特征点出现在初始压密阶段;分析声发射幅度参数发现,卸载时幅度变化为加载时的24倍,卸载时声发射活动更为剧烈;在循环加卸载中砂岩和泥岩的Felicity比先减小后增加再减小且始终小于1,Felicity效应显著;声发射的平静期并不是所有岩石的必有属性,以声发射的平静期作为岩石破坏的前兆判据并不适用于软弱泥岩。(4)在控制应力进行一次加载时岩石发生了剪切破坏;在控制位移进行加载时,发生了压-剪破坏;循环加卸载时岩体发生拉伸破坏,声发射点组成的线条与劈裂形状吻合。(5)对砂岩A1和泥岩B2进行数值模拟,得到加载方式不同岩石破坏模式不同,破碎尺寸也受加载方式的影响;AE事件集中发生在塑性阶段,峰值应力前占到90%,峰后破坏阶段只占10%。
[Abstract]:In this paper, two groups of sandstone and mudstone cores in the roof and bottom of Xinhu mine bottom yard are taken, and the methods of theoretical analysis, laboratory uniaxial compression test and RFPA2D numerical simulation are used. Acoustic emission (AE) of sandstone and mudstone under uniaxial compression is studied under different stress paths. The AE characteristics of rock and the evolution of AE point during loading and compression are obtained by experimental data. Based on this analysis, the change of mechanical properties of rock, its deformation, damage and failure, and the comparison of failure modes are analyzed. The main work of this paper is as follows: 1) according to the uniaxial loading tests of sandstone and mudstone under different stress paths, The sandstone and mudstone have all gone through initial compaction stage, elastic stage, plastic stage and post-peak failure stage in the process of loading and failure, and with the increase of uniaxial compressive strength of rock, The difference of acoustic emission characteristics between sandstone and mudstone during damage and failure under different stress paths is analyzed. The results show that the maximum AE event number of mudstone does not coincide with the peak stress of rock, the peak value of AE event number of sandstone coincides with the peak stress of rock, and the peak energy of sandstone is earlier than the peak value of AE event number. The peak value of AE event and the peak value of energy of mudstone are coincident with each other.) by analyzing the variation of stress during cyclic loading and unloading, it is found that the characteristic point of Kaiser effect of sandstone appears at 21% of the peak stress, that is, at the beginning of elastic stage. The characteristic points of Kaiser effect of mudstone appear in the initial compaction stage and the amplitude parameters of acoustic emission are analyzed. It is found that the amplitude of unloading is 24 times of that of loading and the activity of acoustic emission is more intense during unloading. During cyclic loading and unloading, the Felicity of sandstone and mudstone decreases first and then increases and then decreases, and is always less than 1% Felicity. The quiet period of acoustic emission is not a necessary attribute of all rocks. Taking the quiet period of acoustic emission as the precursor criterion of rock failure is not suitable for weak mudstone. 4) when the control stress is under one loading, the shear failure occurs in the rock, and when the controlled displacement is loaded, the compressive shear failure occurs. Under cyclic loading and unloading, tensile failure occurs in the rock mass, and the lines of acoustic emission point are consistent with the splitting shape. The numerical simulation of sandstone A1 and mudstone B2 is carried out. The results show that different rock failure modes are different in different loading modes. The fracture size is also affected by the loading mode. AE events mainly occur in the plastic stage, the peak stress accounts for 90% before the peak stress, and only 10% at the post-peak failure stage.
【学位授予单位】：安徽理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TD315

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