岩石破坏细观机理及失稳前兆声发射特征的研究

发布时间：2018-05-23 16:21

本文选题：实时加载CT扫描 + 细观破坏过程　；参考：《太原理工大学》2013年博士论文

【摘要】：岩石破坏过程和机理一直是岩石力学等学科的研究热点和难点之一。岩石的宏观破坏与其内部细观结构及其缺陷密切相关。要想弄清岩石失稳机理,就必须从岩石破裂的细观角度来研究岩石内部微裂纹产生、扩展、破坏过程。而由于岩石内部微破裂很难直接动态观测,声发射方法便成了研究岩石变形破坏过程中微破裂动态过程的有效工具,但由于对声发射产生机制及与破坏之间的关系缺乏本质认识,目前应用声发射技术对岩石内部微破坏的研究主要依靠推测。因此,研究岩石破坏细观机理和研究声发射与细观破坏之间的关系,对岩石破坏机理的认识及声发射技术在破坏失稳监测、预测中的应用具有重要的理论和实际意义。本文采用实时加载CT扫描方法研究了峰值载荷前岩石内部微裂纹在不同加载阶段的发展规律及与声发射之间的关系,采用非实时加载CT扫描方法研究了峰值载荷后岩石内部贯通裂纹的赋存特征及与声发射之间的关系,揭示了岩石破坏机理及声发射事件产生原因,建立了声发射与破坏之间的关系,应用声发射技术对大尺寸试件破坏过程进行了研究,提出了破坏失稳前兆的声发射特征,最后,应用RFPA数值软件从破坏过程和应力分布的角度探讨了岩石破坏过程中裂纹扩展的三维空间规律及破坏机理。主要研究工作总结为以下几个方面：(1)研制了与CT系统和声发射测试分析系统配套的加载装置,实现了实时加载CT扫描和声发射实时采集同步进行。利用该实验系统观测到了不同加载阶段泥岩、砂岩试件在峰值载荷前岩石内部原生裂纹、孔隙等在加载过程中的变化规律和声发射分布特征。研究了微破坏的起裂、扩展规律及颗粒在裂纹扩展中的作用,分析了表面裂纹破坏形式与岩石内部细观结构间的关系,分析了声发射事件产生的原因及声发射时空分布特征与细观破坏之间的关系,建立了声发射能量与细观破坏类型之间的关系。(2)采用非实时加载CT扫描方法分析了花岗岩、辉长岩在峰值载荷后其内部贯通裂纹赋存特征及声发射时空分布特征,研究了破坏的起裂、扩展规律及颗粒在裂纹扩展中的作用,分析了岩石内部贯通裂纹的扩展规律,研究了声发射的空间分布特征与细观破坏、贯通裂纹扩展过程之间的关系,建立了声发射振铃计数与裂纹宽度之间的关系。(3)应用声发射技术研究了大尺寸的细砂岩、辉长岩和花岗岩破坏过程及失稳前兆的声发射特征,根据声发射时空分布特征,结合岩石最终破坏情况,提出将声发射累积形成从集区的特征作为破坏失稳的第一个前兆,将声发射事件空间累积形成空白区的特征作为破坏失稳的第二个前兆,按次序依次对破坏失稳进行预测。(4)应用RFPA2D研究了非均匀性对破坏过程及机理的影响,研究了不同均匀性条件下细观微破裂萌生、发展、贯通的过程及宏观裂纹贯通、扩展的机制。应用RFPA3D从应力场演化及裂纹三维空间扩展的角度分析了岩石破坏过程中微破裂萌生、发展、贯通的过程及宏观裂纹相互之间的作用。
[Abstract]:Rock failure process and mechanism have always been one of the hotspots and difficulties in rock mechanics. The macro damage of rock is closely related to its internal meso structure and its defects. To clarify the mechanism of rock instability, it is necessary to study the formation, expansion and failure process of rock micro cracks from the meso angle of rock fracture. The internal micro fracture of stone is difficult to be observed directly and dynamically. Acoustic emission method is an effective tool to study the dynamic process of micro fracture in the process of rock deformation and failure. However, due to the lack of essential understanding of the mechanism of acoustic emission and the relationship with damage, the research on the application of acoustic emission technology to the internal micro failure of rock and rock mainly depends on the speculation. The study of the mechanism of rock failure and the study of the relationship between acoustic emission and meso damage, the understanding of rock failure mechanism and the application of acoustic emission technology in failure monitoring and prediction are of great theoretical and practical significance. In this paper, the real time loading CT scanning method is used to study the micro cracks in the rock before the peak load. The relationship between the development law of the loading stage and the acoustic emission is studied by using the non real-time loading CT scanning method. The relationship between the occurrence characteristics and the acoustic emission after the peak load is studied. The mechanism of rock failure and the cause of the acoustic emission events are revealed, and the relationship between the acoustic emission and the damage is established. The acoustic emission technology has been studied on the failure process of large size specimen, and the acoustic emission characteristics of the failure precursor are proposed. Finally, the three-dimensional space law and failure mechanism of the crack propagation in the process of rock failure are discussed by using the RFPA numerical software from the angle of the failure process and the stress distribution. The main research work is summarized as the following aspects. (1) the loading device is developed with the CT system and the acoustic emission test and analysis system. The real-time loading CT scan and acoustic emission real-time acquisition synchronization are carried out. The experimental system has been used to observe the original cracks in the rock and the pore in the rock before the peak load, and the variation of the pore in the loading process. The distribution characteristics of the harmonic emission are studied. The crack initiation, the propagation law and the effect of the particles in the crack propagation are studied. The relationship between the form of the surface crack damage and the meso structure of the rock is analyzed. The causes of the acoustic emission events and the relationship between the space-time distribution characteristics of the acoustic emission and the meso damage are analyzed, and the acoustic emission energy is established. The relationship with the meso damage type. (2) using the non real time loading CT scanning method, the characteristics of the interconnected crack occurrence and the acoustic emission spatio-temporal distribution of the gabbro were analyzed after the peak load, and the crack initiation, the expansion law and the effect of the particles in the crack expansion were studied. The relationship between the spatial distribution characteristics of acoustic emission and the mesoscopic damage and the process of crack propagation is studied. The relationship between the number of acoustic emission ringing and the crack width is established. (3) the acoustic emission technique is used to study the damage process of the large size fine sandstone, the gabbro and granite and the acoustic emission characteristics of the instability precursors, and the sound is based on sound. The characteristics of space-time distribution, combined with the ultimate failure of rock, are proposed to form the characteristics of acoustic emission from the set area as the first precursor of failure instability. The characteristics of the acoustic emission event space are accumulated to form the second precursors of the failure instability, and the failure instability is predicted in order by order. (4) the application of RFPA2D is studied. The effects of non-uniformity on the failure process and mechanism are studied. The process of micro fracture initiation, development, penetration and the mechanism of macro crack penetration and expansion are studied under the conditions of different homogeneity. The process of micro fracture initiation, development and penetration in the process of rock breaking through the evolution of stress field and the three-dimensional space expansion of cracks are analyzed by using RFPA3D. The interaction between macroscopic cracks.
【学位授予单位】：太原理工大学
【学位级别】：博士
【学位授予年份】：2013
【分类号】：TU45

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