含水岩石损伤破坏声发射特征试验研究

发布时间：2019-04-17 12:43

【摘要】：目前,国内外大量学者围绕声发射技术应用于岩石损伤监测进行了广泛研究,促进了这一技术的发展和应用,众所周知,自然界中的岩石均含有一定量的水分,地下水是影响岩体流变及工程稳定性的重要因素。水的存在,使声发射信号变得更加复杂,针对这一问题,本文在含水岩石破裂过程声发射试验的基础上,对不同含水量岩样损伤破坏声发射特征进行了研究。首先,对不同含水量完整岩样进行单轴压缩试验,同时使用声发射实验仪器对整个实验过程的声发射数据进行监测和记录。选取砂岩、花岗岩各15块并用烘干设备烘干,分别选出3块作为干燥岩样,其余进行泡水处理,制成干燥到饱和之间不同含水量的试样并进行试验。试验结果表明干燥完整岩样声发射事件数与其加载时间存在以下几个阶段：第一阶段,试验初始阶段声发射事件数增长缓慢,声发射事件数变化并不明显；第二阶段,声发射事件数变化率大于第一阶段,并趋于稳定；第三阶段,试验即将结束前,声发射事件数变化率变大,声发射事件数瞬间达到顶峰直至实验结束。由于加载速率分别为砂岩20kN/min、花岗岩30kN/min的自动控制系统,因此,声发射事件数与应力的关系也遵循这三个阶段。对于其它含水量岩石,其强度会随含水量的增加而减小,声发射事件数也随含水量的增加而减小,砂岩岩样的强度明显小于花岗岩,其声发射事件数也少于花岗岩,但其含水量要大于花岗岩,含水量对花岗岩声发射特征的影响也要小于其对砂岩的影响。砂岩的破坏形态会随着含水量的增加而破坏的更完全,但总体破坏形态不变；花岗岩的破坏形态与含水量多少关系不大。其次,进行了带预制裂纹不同含水量砂岩、花岗岩单轴压缩声发射特征实验研究。实验结果显示,带预制裂纹岩石声发射特征与完整岩样声发射特征比较相似,但带预制裂纹的岩样声发射事件数的增长率第一与第二阶段的拐点比较靠后,由于其强度也弱于完整岩样,因此,其声发射事件数也少于完整岩样。带预制裂纹的砂岩破坏形态是由试样上下两端至预制裂纹根部各有一道裂纹,其含水量越大,破坏越完全,部分区域会有粉碎性破坏。花岗岩的破坏形态与砂岩相似,但其裂纹相对较少,几乎没有粉碎性破坏。
[Abstract]:At present, a large number of scholars at home and abroad have carried out extensive research on the application of acoustic emission technology to rock damage monitoring, which has promoted the development and application of this technology. As we all know, rocks in nature contain a certain amount of water. Groundwater is an important factor affecting the rheology and engineering stability of rock mass. The acoustic emission signal becomes more complicated because of the existence of water. In this paper, the characteristics of damage and failure of rock samples with different water content are studied on the basis of acoustic emission test in the process of fracture of water-bearing rock. First, uniaxial compression tests were carried out on intact rock samples with different water content. At the same time, acoustic emission data of the whole experiment process were monitored and recorded by acoustic emission experiment instrument. 15 pieces of sandstone and granite were selected and dried by drying equipment. Three samples were selected as dry rock samples, and the others were treated with bubble water. The samples with different moisture content between drying and saturation were made and tested. The experimental results show that there are several stages between the number of acoustic emission events and the loading time of dry intact rock samples. In the first stage, the number of acoustic emission events increases slowly in the initial stage of the experiment, but the change of the number of acoustic emission events is not obvious. In the second stage, the change rate of the number of acoustic emission events is larger than that of the first stage and tends to be stable, and in the third stage, the change rate of the number of acoustic emission events becomes larger before the end of the experiment, and the number of acoustic emission events reaches its peak instantly until the end of the experiment. Because the loading rate is 20kN / min for sandstone and the automatic control system for granite 30kN/min, the relationship between the number of acoustic emission events and stress also follows these three stages. For other rocks with water content, the strength will decrease with the increase of water content, and the number of acoustic emission events will also decrease with the increase of water content. The strength of sandstone samples is obviously smaller than that of granite, and the number of acoustic emission events of sandstone samples is also less than that of granite. However, the water content of the granite is larger than that of granite, and the influence of water content on the acoustic emission characteristics of granite is smaller than that of sandstone. The failure form of sandstone will be more complete with the increase of water content, but the overall failure pattern will not change, and the failure form of granite has little relation with the amount of water content. Secondly, the acoustic emission characteristics of sandstone with prefabricated cracks and granite under uniaxial compression are studied. The experimental results show that the acoustic emission characteristics of rock with prefabricated cracks are similar to those of intact rock samples, but the growth rate of acoustic emission events of rock samples with prefabricated cracks is lower than that of the second stage. As its strength is weaker than that of intact rock samples, the number of acoustic emission events is also less than that of intact rock samples. The failure pattern of sandstone with prefabricated cracks is that there is a crack from the upper and lower ends of the specimen to the root of the prefabricated crack. The larger the water content, the more complete the failure will be, and there will be comminuted failure in some areas. The failure pattern of granite is similar to that of sandstone, but its crack is relatively few, and there is almost no comminuted failure.
【学位授予单位】：东北大学
【学位级别】：硕士
【学位授予年份】：2013
【分类号】：TU45

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