| 含预制单裂隙花岗岩的真三轴单面临空岩爆试验研究 |
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| 引用本文： | 罗丹旎,卢思航,苏国韶,陶洪辉.含预制单裂隙花岗岩的真三轴单面临空岩爆试验研究[J].岩土力学,2023,44(1):75-87. |
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| 作者姓名： | 罗丹旎 卢思航 苏国韶 陶洪辉 |
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| 作者单位： | 1. 中国能源建设集团广西电力设计研究院有限公司，广西 南宁 530007；2. 广西大学 土木建筑工程学院，广西 南宁 530004；
3. 广西大学 广西岩溶区水安全与智慧调控工程研究中心，广西 南宁 530004 |
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| 基金项目： | 中国博士后科学基金资助（No. 2018M633299）；国家自然科学基金资助（No. 52179125，No. 51709050）。 |
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| 摘 要： | 通过开展含预制单裂隙花岗岩的真三轴单面临空岩爆试验，并利用高速摄像系统和声发射（acoustic emission，简称AE）系统监测岩爆过程，探究了不同产状裂隙岩石的破坏模式、强度变形和声发射演化特性，分析了裂隙产状与岩爆过程及弹射动能之间的关系，对比了含裂隙岩石岩爆发生机制与无裂隙完整岩石的差异。有关力学特性的分析表明，随着裂隙倾角的减小，岩样破坏模式大体呈现由“内剪外劈”向“Z型斜剪”变化的趋势，裂隙对岩石强度的削弱作用不断增大。当裂隙倾角小于30°时，岩石峰值应力普遍仅为完整岩样的一半左右；小倾角裂隙的长度越大，岩样岩板劈裂现象变得显著，形成岩爆坑略微变大，且强度折减幅度越大，峰值轴向应变相应变小；裂隙位置向临空面靠近会加剧岩板的劈裂效应，塑性阶段普遍会产生较大变形并萌生大量裂纹，当裂隙已出露且切断临空面将不易形成岩爆坑。有关岩爆过程及弹射动能的分析表明，随着裂隙倾角的减小，岩样弹射动能呈现先显著降低后小幅回升的变化规律，30°倾角为转变拐点；岩样内部裂隙距临空面越近，裂隙岩样的弹射动能越小；树脂填充裂隙使得岩样弹射动能极大提升，而水泥填充的则无明显提升。有关声发射特征的分析表...
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| 关 键 词： | 岩爆 岩石 裂隙 声发射 弹射动能 |
| 收稿时间： | 2022-03-08 |
Experimental study on rock burst of granite with prefabricated single crack under true-triaxial stress condition with a free face |
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| LUO Dan-ni,LU Si-hang,SU Guo-shao,TAO Hong-hui.Experimental study on rock burst of granite with prefabricated single crack under true-triaxial stress condition with a free face[J].Rock and Soil Mechanics,2023,44(1):75-87. |
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| Authors: | LUO Dan-ni LU Si-hang SU Guo-shao TAO Hong-hui |
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| Institution: | 1. China Energy Engineering Group Guangxi Electric Power Design Institute Co., Ltd., Nanning, Guangxi 530007, China; 2. School of Civil and Architecture Engineering, Guangxi University, Nanning, Guangxi 530004, China; 3. Guangxi Provincial Engineering Research Center of Water Security and Intelligent Control for Karst Region, Guangxi University, Nanning, Guangxi 530004, China |
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| Abstract: | A rock burst experiment of granite with prefabricated single crack under the true-triaxial stress condition with a free face was carried out in this paper, and the rock burst process was monitored by high-speed camera system and acoustic emission (AE) system. The failure mode, strength, deformation and AE evolution characteristics of the rocks with different orientations of cracks were investigated. The relationships between crack orientation and rock burst process and ejection kinetic energy was analyzed. The rock burst mechanisms of the rocks with prefabricated single crack and the intact rocks were compared. The analysis of mechanical properties shows that, with the decrease of crack dip angle, the failure mode of rock samples generally changes from "internal shear and external splitting" to "Z-type oblique shear", and the weakening effect of cracks on rock strength is increasing. When the crack dip angle is less than 30°, the peak stress of rock is generally only about half that of the intact rock samples. The larger the length of the small-dip-angle crack is, the more obvious the splitting phenomenon of the rock slab will be, the slightly larger the rock burst pit will be, the larger the strength reduction amplitude will be, and the smaller the peak axial strain will be. The crack close to the free surface of rock samples will aggravate the splitting effect of the rock slab, large deformation and numerous cracks will occur in the plastic stage generally. When the crack is exposed and cuts off the free surface, it will be difficult to form rock burst pits. The analysis of rock burst process and ejection kinetic energy shows that, with the decrease of crack dip angle, the ejection kinetic energy of rock samples decreases significantly first and then increases slightly, the dip angle of 30° is the turning point of transformation. The closer the internal cracks of the rock sample are to the free surface, the smaller the ejection kinetic energy of the rock sample will be. The resin-filled crack greatly increases the ejection kinetic energy of rock sample, but not when cement fills cracks. The analysis of AE characteristics shows that, the longer length and the smaller dip angle of the crack are, the larger the time proportion of "quiet period" to rock burst process is, and the smaller the absolute energy proportion of rock burst in the post-peak stage is. If the crack is close to rock free surface, two "quiet periods" generally appear, and one more sudden rise will also appear in the AE absolute energy evolution curve. With the increase of crack dip angle, the duration of the initial fluctuation stage of b value of rock samples with crack becomes longer, the decrease rate of decline stage becomes larger, and the minimum b value point is closer to the rock burst time. In general, the mechanism of strain-type rock burst in rocks with cracks differs from that in intact rocks. The mechanism of strain-type rock burst in rocks with cracks can be classified into two types: shear-fracture type and tension-slabbing type. The research results provide a scientific basis for the mechanism analysis of rock burst disaster of fractured rocks and the early-warning by using AE technology. |
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| Keywords: | rock burst rock crack acoustic emission ejection kinetic energy |
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