| 单轴压缩条件下含三叉裂隙类岩石试样力学特性的细观研究 |
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| 引用本文： | 李露露,高永涛,周喻,金爱兵.单轴压缩条件下含三叉裂隙类岩石试样力学特性的细观研究[J].岩土力学,2018,39(10):3668-3676. |
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| 作者姓名： | 李露露 高永涛 周喻 金爱兵 |
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| 作者单位： | 北京科技大学 金属矿山高效开采与安全教育部重点实验室，北京 100083 |
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| 基金项目： | 国家青年科学基金(No. 51504016)；中央高校基本科研业务费专项资金(No. FRF-BD-17-007A)；国家自然科学基金(No. 51674015)。 |
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| 摘 要： | 三叉裂隙是自然界普遍存在的一种岩体缺陷形式，其对岩体的力学特性有重要影响。对含预制三叉裂隙的水泥砂浆试样进行室内单轴压缩试验，配合使用摄像机拍摄裂纹的起裂、扩展、贯通过程，通过数字图像技术处理获取试样的应变场云图，并结合PFC2D程序研究不同?、? 条件下试样的强度特征、裂纹模式和裂纹演化扩展规律。研究表明：三叉裂隙对试样单轴抗压强度有明显的削弱作用。当? 恒定为120°时，试样在? = 30°时达到最大抗压强度；当? 恒定为90°时，随?增大，试样抗压强度呈先减小后增大的趋势，且当? = 45°时达到最大抗压强度。试样产生的裂纹可分为3类，分别是张拉型裂纹(Ⅰ型裂纹)、剪切型裂纹(Ⅱ型裂纹)、混合型裂纹(Ⅲ型裂纹)。这3类裂纹通常从裂隙尖端开始产生，并且Ⅰ型裂纹沿加载方向扩展，通常未扩展至试样边界；Ⅱ型和Ⅲ型裂纹通常与加载方向呈一定角度扩展至试样边界。通过对裂纹的几何形态和组成宏观裂纹的微裂纹成分的分析，得知导致含三叉裂隙试样在单轴压缩条件下失效的是张拉破坏。数字图像技术得到的应变云图表明，当载荷达到一定阶段，裂隙尖端出现应力集中，微破裂开始发育并聚集成微破裂区，微破裂区扩大产生宏观裂纹。通过对主应变和剪应变云图分析，发现导致试样失效的是张拉破坏，剪应变在裂纹扩展过程中的影响较小。
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| 关 键 词： | 岩石 三叉裂隙 单轴压缩 颗粒流程序(PFC) 数字图像技术 |
| 收稿时间： | 2018-05-16 |
Meso-scale modelling mechanical properties of rock-like material containing trident cracks under uniaxial compression |
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| LI Lu-lu,GAO Yong-tao,ZHOU Yu,JIN Ai-bing.Meso-scale modelling mechanical properties of rock-like material containing trident cracks under uniaxial compression[J].Rock and Soil Mechanics,2018,39(10):3668-3676. |
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| Authors: | LI Lu-lu GAO Yong-tao ZHOU Yu JIN Ai-bing |
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| Institution: | Key Laboratory of Ministry of Education for Efficient Mining and Safety of Metal Mine, University of Science and Technology Beijing, Beijing 100083, China |
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| Abstract: | Trident cracks are the ubiquitous form of rock mass defect in nature, it has a significant influence on mechanical properties of rock mass. Uniaxial compression tests were conducted on cement mortar samples containing prefabricated trident cracks. The crack initiation, propagation and coalescence processes were recorded by a camera at the same time. The strain fields of the specimens were obtained by the digital image correlation (DIC) method. Combined with the PFC2D software, we studied the strength characteristics, crack modes and crack propagation rules of specimens under different angles of ? and ?. The results show that trident cracks have an obvious weakening effect on uniaxial compressive strength of specimens. When ? is constant at 120°, the sample reaches the maximum compressive strength when ? is 30°. When ? is constant at 90°, the compressive strength of the sample decreases first and then increases with increasing ?, and the maximum compressive strength is achieved when ? is 45°. There are three types of cracks generated in the specimens, including tensile crack (mode I), shear crack (mode II) and mixed crack (mode III). These three types of cracks usually initiate from the tip of crack. The mode I crack propagates along the loading direction normally and usually does not extend to the sample boundary, but the mode II and mode III cracks normally propagate to the sample boundary at a certain angle to the loading direction. By analysing the geometry of cracks and the composition of microcracks that further leads to macrocracks, it is known that the failure of the specimen containing trident cracks under uniaxial compression is tensile failure. The strain fields obtained by the DIC show that when the load reaches a certain stage, stress concentration occurs at the tip of a crack, then microcracks begin to develop and form micro-cracked areas, and finally, macro-cracks are generated. Through the analysis of the principal strain and shear strain fields, it is found that the failure of specimens is tensile failure, and the shear strain has little influence on the crack propagation process. |
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| Keywords: | rock trident cracks uniaxial compression particle flow code (PFC) digital image correlation |
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