脆性岩石受载破碎声发射与电磁辐射特性试验研究

发布时间：2018-05-05 18:58

本文选题：岩石破碎 + 动静载荷　；参考：《湖南科技大学》2017年硕士论文

【摘要】：岩石破碎声发射和电磁辐射现象是岩石受载作用获得能量后,将存储的能量以声能和电磁能释放的两种物理效应。针对这些物理效应的研究,目前主要集中在对岩石受载产生的声发射或电磁辐射单一特性方面上,而对岩石在受不同载荷情况下两者的同步研究的较少。为探讨受不同载荷时脆性岩石破碎表现出来的声电特性,本文分别开展单轴静载下压头、刀具作用下以及动静载荷作用下不同脆性岩石破碎声发射与电磁辐射试验,根据采集的声电信号对岩石破碎全过程的声发射、电磁辐射特性进行探讨,然后分析总结脆性岩石受不同载荷作用下破碎特点以及产生的声发射、电磁辐射特征参量变化。论文主要内容及结论如下:(1)运用破碎力学理论分析了静载作用下刀具侵入力的影响因素及动载作用下岩石应力波的获取过程,探讨了岩石受载荷作用下破碎过程的声发射产生机制,得出声发射率和应力强度因子、裂纹长度增量的具体关系;分析了破碎过程电磁辐射信号特点,探讨了电磁辐射幅值与岩石属性参数之间的关系,得到了电磁辐射幅值随岩石弹性模量增加而增大,岩石受载应力越大,电磁辐射幅值反而越小;电磁辐射幅值随岩石弹模的增大趋势要比随岩石泊松比的增大趋势大得多。(2)选用典型脆性花岗岩为研究对象对其开展了压头与刀具作用下的声发射、电磁辐射试验。结果表明:压头与刀具作用下岩石受载破坏产生声发射、电磁辐射信号变化规律具有差异性,当岩石发生破坏前,平端压头加载作用下岩石声发射振铃计数率和能量率随载荷增加逐渐增大,电磁辐射信号随载荷增加逐渐增大,而刀具静力侵入岩石声发射振铃计数率和能量率呈跃进式变化,电磁辐射信号会出现突增现象。(3)对比分析压头与刀具作用下岩石受载过程声发射和电磁辐射特征结果可知:岩石受载破坏过程中声发射和电磁辐射均与载荷存在正相关耦合关系,二者具有较好的相关性,能很好反映岩石的变形破坏过程,但岩石产生的电磁辐射信号比声发射信号要丰富得多、出现也早,电磁辐射比声发射有着更广泛的产生机制。(4)在静载作用下,在加载初期岩石有少量的声发射、电磁辐射信号出现,不同岩样破坏过程中都伴随着声发射、电磁辐射信号的产生,但强度高的岩样,在破坏过程中接受到的声发射、电磁辐射信号峰值大,不同试样间大能量的事件往往对应少的振铃计数,多的振铃计数往往对应能量小的事件,试验过程中接收的电磁辐射脉冲数信号和时间的变化规律具有良好的对应关系。(5)在动载作用下,对比同一种试样声电信号发现,岩石应力的峰值和声发射信号峰值大概处于同一时间段,但是电磁辐射信号的峰值比应力峰值、声发射信号峰值的时间都要早些。(6)对比分析动静载荷岩石破碎声电试验数据结果,表明声电信号的每一次较大的跳跃波动代表岩石的一次破碎,试验过程中声发射、电磁辐射信号都能较好的反映试样的受力状态和变形破坏程度,和试样的破碎形态是相互对应的,可以通过电磁辐射和声发射技术监测岩石的受力及破坏情况,在工程实践中能够起到一定的预测预警作用。
[Abstract]:The acoustic emission and electromagnetic radiation of rock breaking are the two physical effects that the stored energy is released by sound energy and electromagnetic energy after the rock is loaded, and the research on these physical effects is mainly focused on the single characteristic of acoustic emission or electromagnetic radiation produced by rock loading, and the rock is loaded with different loads. In order to investigate the acoustic and electrical characteristics of brittle rocks under different loads, the acoustic emission and electromagnetic radiation of different brittle rocks under the action of the tool and the dynamic and static loads are tested in this paper. The characteristics of the acoustic emission and electromagnetic radiation of the process are discussed, and then the characteristics of the brittle rocks under different loads, the acoustic emission and the characteristic parameters of the electromagnetic radiation are analyzed. The main contents and conclusions of this paper are as follows: (1) the influence factors and the dynamic load of the tool invasion force under the static load are analyzed by the theory of fracture mechanics. Using the process of obtaining the rock stress wave, the mechanism of acoustic emission produced by the rock under loading is discussed, and the specific relation between the acoustic emission rate and the stress intensity factor and the crack length increment is obtained. The characteristics of the electromagnetic radiation signal in the crushing process are analyzed, and the relationship between the electromagnetic radiation amplitude and the rock property parameters is discussed. The amplitude of electromagnetic radiation increases with the increase of the elastic modulus of rock. The larger the load stress is, the smaller the amplitude of the electromagnetic radiation, the increasing trend of the electromagnetic radiation amplitude with the rock mass ratio is much larger than that of the rock Poisson's ratio. (2) the typical brittle granite is selected as the research object under the action of the pressure head and the cutting tool. Acoustic emission and electromagnetic radiation test. The results show that the load of rock under the action of the pressure head and the tool produces acoustic emission, and the change law of electromagnetic radiation signal is different. When the rock is damaged, the rate and the energy rate of the sound emission ringing increase with the load, and the electromagnetic radiation signal increases with the load. Adding gradually, the counting rate and the energy rate of the acoustic emission ringing of the rock cutters show a leap forward change, and the electromagnetic radiation signal will appear abrupt increase. (3) the characteristics of acoustic emission and electromagnetic radiation of rock loading process under the action of pressure head and cutting tools are compared and analyzed. There is a positive correlation coupling relationship between the two ones, which has good correlation and can well reflect the deformation and failure process of rock, but the electromagnetic radiation signals produced by the rock are much richer than acoustic emission signals, and the electromagnetic radiation has a more extensive generation mechanism than acoustic emission. (4) under the static loading, there are a small amount of rock at the initial stage of loading. Acoustic emission and electromagnetic radiation signal occur. In the process of damage of different rock samples, acoustic emission and electromagnetic radiation are produced, but the high intensity samples are received by acoustic emission during the failure process, the peak of electromagnetic radiation signal is large. The events of large energy in different samples often correspond to few ringing counts, and the number of ringing counts often corresponds to the energy. There is a good correspondence relationship between the number of electromagnetic radiation pulses received in the test process and the changing law of time. (5) under the action of dynamic load, the peak of rock stress and the peak of acoustic emission signal are probably in the same period, but the peak value of the electromagnetic radiation signal is compared to the stress peak under the action of dynamic load. Value, the time of the peak of acoustic emission signal should be earlier. (6) comparing and analyzing the results of the acoustic and electroacoustic test data of rock breaking and static load, it shows that each big jump wave of the acoustic signal represents the one break of the rock. The acoustic emission and electromagnetic radiation signal in the test process can better reflect the stress state and the degree of deformation and damage of the specimen. The fracture morphology of the specimen is corresponding to each other. It can monitor the stress and damage of the rock by electromagnetic radiation and acoustic emission technology, and can play a certain predictive and early warning role in the engineering practice.

【学位授予单位】：湖南科技大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TD315

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