岩石声发射及分形特征试验研究

发布时间：2018-05-01 14:23

本文选题：声发射 + 关联维数　；参考：《成都理工大学》2017年硕士论文

【摘要】：岩石是一种天然地质体,经过亿万年的构造运动与风化剥蚀,形成如今非连续的,各向异性的,受环境条件影响的复杂体。岩石声发射作为岩石损伤位置的外在声学现象,损伤破裂信息丰富。分形作为岩石力学的一个崭新分支学科,是研究复杂无序事物规律的有力工具。研究表明,岩石损伤破坏过程不论是在空间上还是在时间上都是分形的。分析与探讨岩石损伤破坏过程中声发射基本参数和分形参数的特性,有利于进一步了解岩石损伤机理与破裂本质。为了解岩石损伤破坏过程并进一步对岩石的破坏前兆进行预测,本文针对砂岩、辉长岩、花岗岩、灰岩等四类常见岩石进行单轴压缩全过程声发射试验,分析声发射基本参数演化过程与应力或变形阶段的统计关系并识别岩石损伤破坏前兆特征;计算并分析岩石声发射时间序列分形演化规律,并识别岩石损伤破坏前兆特征。主要工作内容及取得的成果如下:(1)以0.1mm/Min的速率对岩石试件进行单轴压缩全过程试验,并实时监测声发射信号。分析与探讨岩石声发射事件数、振铃计数以及能量等三个参数的损伤演化过程,识别岩石损伤破坏前兆特征。(2)岩石试件声发射事件数、振铃计数、能量在压密阶段、弹性变形阶段、加速破坏阶段皆依次增加,且事件数增加最为缓慢,能量激增最为明显。在压密阶段、弹性变形阶段、加速破坏阶段,四类岩石声发射事件数绝对量从小到大皆为砂岩、辉长岩、灰岩、花岗岩;声发射事件数相对量随岩石弹性模量的增加,在压密阶段与弹性变形阶段皆呈现依次增大的现象,而在加速破坏阶段则依次降低。在压密阶段与加速破坏阶段,振铃计数和能量规律性并不太明显,然而在弹性变形阶段,振铃计数平均值、最大值、累计值与能量平均值、最大值、累计值的绝对量皆呈随岩石弹性模量增加而依次增加的现象;声发射振铃计数累计量比值与能量累计量比值也都表现为花岗岩最少,灰岩最多的事实。(3)岩石损伤破坏前兆各声发射参数特征点(s)普遍存在能量累计s点应力比振铃累计计数s点应力比事件数s点应力比的现象,且振铃累计计数特征点总是非常接近岩石的屈服点。对比分析岩石声发射基本参数演化曲线图可知,声发射事件数曲线前兆特征点可能不明显,能量累计曲线可能掩盖微小有效信息而都无法很好的应用,然而振铃累计计数曲线能最直观的、有效的反映岩石损伤过程真实状态。(4)编译程序(GP-m.m)计算相空间维数(m)的取值并分析其影响。当m取值偏小时,则相空间重叠;当m取值过大时,则计算量大大增加,且分形范围变窄,因此取最适相空间嵌入维数m=10。编译程序(GP-D.m)计算不同应变比下岩石损伤破坏全过程相点距离均值和关联维数,分析其演化规律并识别岩石损伤破坏前兆特征。(5)单轴压缩全过程岩石损伤破坏声发射分形参数-相点距离均值,在弹性变形阶段呈现随岩石初始损伤程度大而上升,小而平稳下降的现象;在加速破坏阶段皆激增并在峰值应力处达到最大的现象;在峰后阶段,随应力跌落而下降,随应力台阶而上升,并在残余应力段基本保持稳定。单轴压缩全过程岩石损伤破坏声发射分形参数-关联维数,呈现“波动-上升-下降-激增-波动”的演化规律。(6)声发射分形相点距离均值激增点以及关联维数“V型”拐点可以作为岩石损伤破坏前兆的特征识别点,同时也可作为间接判定岩石屈服点的依据。鉴于岩石声发射基本参数的敏感性、直观性、准确性以及分形参数的稳定性,笔者建议以声发射振铃计数特征点s作为岩石损伤破坏的前兆,以相点距离均值特征点s和关联维数特征点s作为声发射振铃计数特征点识别准确性的验证。(7)基于声发射振铃计数的损伤本构模型可以完整地反映岩石的损伤破坏全过程;基于weibull分布和对数正态分布的本构模型能很好地揭示岩石在峰值应力前的损伤破坏过程。
[Abstract]:Rock is a natural geological body. After hundreds of millions of years of tectonic movement and weathering denudation, it forms a complex body that is discontinuous, anisotropic and affected by environmental conditions. The acoustic emission of rock is an external acoustic phenomenon of rock damage position, and the information of damage and rupture is abundant. As a new branch of rock mechanics, fractal is studied. A powerful tool for the law of complex and disordered things. The study shows that the process of rock damage and failure is fractal in both space and time. The analysis and discussion of the characteristics of the basic acoustic emission parameters and fractal parameters in the process of rock damage and failure is beneficial to further understanding the damage mechanism and fracture nature of rock. The damage process is predicted and the precursors of rock failure are predicted. In this paper, four kinds of common rocks, such as sandstone, gabbro, granite and limestone, are carried out by uniaxial compression full process acoustic emission test, and the statistical relationship between basic parameters of acoustic emission and stress or deformation stage is analyzed and the precursory characteristics of rock damage and damage are identified. The fractal evolution law of rock acoustic emission time series is analyzed and the precursory characteristics of rock damage and damage are identified. The main work contents and achievements are as follows: (1) a single axial compression test of rock specimens is carried out at the rate of 0.1mm/Min, and the acoustic emission signals are monitored in real time. The number of acoustic emission events, ringing count and the counting of rock are analyzed and discussed. The damage evolution process of three parameters, such as energy, identifies the precursory characteristics of rock damage and damage. (2) the number of acoustic emission events, the counting of ringing, the energy in the stage of compaction, the stage of elastic deformation and the accelerated failure stage, and the number of events increases most slowly and the energy increase is most obvious. In the compaction stage, the elastic deformation phase, acceleration. In the stage of failure, the absolute amount of four types of acoustic emission events from small to large are sandstone, gabbro, limestone and granite, and the relative amount of acoustic emission events increases with the increase of the elastic modulus of rock, in the compaction stage and the stage of elastic deformation, but in the stage of accelerated failure, and in the compaction stage and accelerated failure. At the stage, the ringing count and energy regularity are not very obvious. However, in the elastic deformation stage, the mean value, the maximum value, the accumulative value and the energy mean value, the maximum value and the cumulative value all increase in turn with the increase of the elastic modulus of the rock; the ratio of the accumulative amount of the sound emission ringing count to the accumulative energy is also all table. It is the fact that the granite is the least and the limestone has the most. (3) the stress ratio of the accumulative s point stress to the accumulative count s point stress ratio is s point stress ratio, and the cumulative count characteristic point of the ringing is always close to the yield point of the rock, and the rock acoustic emitter base is compared and analyzed. This parameter evolution curve map shows that the premonitory feature points of the acoustic emission event number curve may not be obvious. The accumulative energy curve can not be applied well, but the accumulative counting curve of the ringing can be the most intuitive and effective to reflect the real state of the rock damage process. (4) the compiler program (GP-m.m) calculates the dimension of phase space ( When the value of M is too small, the phase space overlaps. When the value of M is too large, the calculation amount is greatly increased and the fractal range is narrowed. Therefore, the optimum phase space embedding dimension m=10. compiler (GP-D.m) is taken to calculate the mean and correlation dimension of the phase point distance of the whole process of rock damage and damage under different strain ratios and analyze its evolution. The precursory characteristics of rock damage and damage are recognized and identified. (5) the fractal parameters of acoustic emission, the mean value of the phase point distance, in the whole process of uniaxial compression, are increased with the initial damage degree of the rock, and the phenomenon of small and steady descent is shown in the stage of elastic deformation, and the maximum phenomenon is reached at the stage of accelerated failure and the maximum stress at the peak stress. In the post peak period, it falls with the stress drop and rises with the stress step, and is basically stable in the residual stress section. The fractal parameters of acoustic emission are damaged and damaged in the whole process of uniaxial compression. The evolution law of "fluctuation - ascending - descent - Surge - fluctuation" is presented. (6) the mean sharp increase point and correlation of the fractal phase point distance of acoustic emission The dimension "V" inflection point can be used as the feature recognition point for the precursor of rock damage and damage, and can also be used as the basis for indirect determination of rock yield points. In view of the sensitivity, intuition, accuracy and stability of the fractal parameters of the basic parameters of rock acoustic emission, the author suggests that the acoustic emission ringing count feature point s is used as the damage damage of rock. The precursors of the phase point distance mean s and the correlation dimension feature point s are used to verify the recognition accuracy of the acoustic emission ringing count feature points. (7) the damage constitutive model based on the sound emission ringing count can fully reflect the whole process of rock damage and damage, and the constitutive model based on the Weibull distribution and the lognormal distribution can be very good. The damage process of rock before peak stress is revealed.

【学位授予单位】：成都理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TU45

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