| 三轴作用下的小型围岩试件在开挖卸荷过程中的声发射特征 |
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| 引用本文： | 侯公羽,梁金平,荆浩勇,胡涛,张广东,谭金鑫,杨希,张永康.三轴作用下的小型围岩试件在开挖卸荷过程中的声发射特征[J].岩土力学,2019,40(12):4564-4572. |
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| 作者姓名： | 侯公羽 梁金平 荆浩勇 胡涛 张广东 谭金鑫 杨希 张永康 |
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| 作者单位： | 1. 中国矿业大学（北京）力学与建筑工程学院，北京 100083；2. 新疆工程学院 矿业工程与地质学院，新疆 乌鲁木齐 830091 |
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| 基金项目： | 国家自然科学基金面上项目（No.51574247）；国家自然科学基金委员会与神华集团有限责任公司联合资助重点项目（No.U1361210） |
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| 摘 要： | 为了获得巷道围岩开挖卸荷过程中的声发射特征与开挖卸荷状态之间的关系，使用水泥砂浆厚壁圆筒围岩试样，开展开挖卸荷条件下3种不同卸荷速度的声发射试验研究。利用自主研发的小型巷道围岩开挖卸荷模型试验系统，声发射系统及变形监测系统采集试样卸荷过程中的声发射时频信号及变形信息，并对声发射b值进行研究。研究发现：（1）试验过程具有4个特征阶段：加载段―维持段Ⅰ―卸荷段―维持段Ⅱ，这4个阶段与振铃累计曲线有良好对应关系。（2）加载段，高频高幅信号较多，分布范围广，试样内部原始裂隙在三向应力作用下压密明显；维持段Ⅰ，高频高幅信号明显减小，分布范围变窄，试样三向持续压密，变形微小；卸荷段，高、低频信号增多，幅度增加，应变率较高，变形增加速度快，卸荷对试样内侧影响效应更显著；维持段Ⅱ，较慢速卸荷的高幅信号持续增多，内外侧以较低应变率持续产生变形。（3）卸荷速度越大，卸荷段振铃累计曲线出现“陡升”的幅度越高，维持段Ⅱ“陡升”出现越早，幅度越小。（4）卸荷速度增大，b值整体量值减小且越趋于小波幅平稳变化，相对声发射大事件占比提高，破裂尺度更大。
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| 关 键 词： | 厚壁圆筒围岩试样 开挖卸荷 声发射 峰值频率 幅度 b值 |
| 收稿时间： | 2018-10-29 |
Acoustic emission characteristics of thick-walled cylinder specimen subjected to triaxial loading during excavation unloading |
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| HOU Gong-yu,LIANG Jin-ping,JING Hao-yong,HU Tao,ZHANG Guang-dong,TAN Jin-xin,YANG Xi,ZHANG Yong-kang.Acoustic emission characteristics of thick-walled cylinder specimen subjected to triaxial loading during excavation unloading[J].Rock and Soil Mechanics,2019,40(12):4564-4572. |
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| Authors: | HOU Gong-yu LIANG Jin-ping JING Hao-yong HU Tao ZHANG Guang-dong TAN Jin-xin YANG Xi ZHANG Yong-kang |
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| Institution: | 1. School of Mechanics and Civil Engineering, China University of Mining and Technology(Beijing), Beijing 100083, China;
2. School of Mining Engineering and Geology, Xinjiang Institute of Engineering, Urumqi, Xinjiang 830091, China |
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| Abstract: | In order to obtain the relationship between the characteristics of acoustic emission (AE) and the unloading state of surrounding rock during roadway excavation, AE monitoring test was carried out during excavation unloading with three different unloading rates using thick-walled cylinder roadway surrounding rock samples made of cement mortar. The self-developed tunnel test system of excavating and unloading of small roadway surrounding rock is equipped with AE system and deformation monitoring system to collect AE time-frequency signals and deformation information of samples during the unloading process. In addition, the b values were also studied. The results show that: 1) The test process has four stages: loading stage, maintenance stage I, unloading stage and maintenance stage II. These four stages correspond well to the cumulative ringing curve. 2) In the loading stage, there are many high frequency and high amplitude signals, and the distribution range is wide. The original crack in the sample is obviously compacted under the pressure of three-direction. After that the high frequency and amplitude signals reduce obviously and the distribution range is also reduced, the sample continues to be compacted under three-direction, and the deformation is small. In the third stage, the signals with high and low frequency and their amplitude increase. The strain rate is high and the deformation increases rapidly, the unloading effect is more significant accordingly. In the maintenance stage II, the high-amplitude signals continue to increase, and the deformation of the inner and outer sides increase continuously with lower speed, when the unloading speed is slow.
3) The bigger the unloading speed is, the higher the amplitude of "steep rise" appears in the ring cumulative curve of the unloading stage, the earlier the amplitude of "steep rise" appears in the ring cumulative curve of maintenance stage II, the smaller the amplitude is. 4) With the increase of unloading rate, the magnitude of b value tends to decrease and varies steadily as a whole, which indicate that the proportion of big AE events are increased, and the fracture scale is larger. |
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| Keywords: | thick-walled cylinder roadway surrounding rock sample excavation unloading acoustic emission peak frequency amplitude b value |
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