| 压缩荷载下泥岩裂缝演化规律的CT试验研究 |
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| 引用本文： | 王传洋,杨春和,衡 帅,冒海军.压缩荷载下泥岩裂缝演化规律的CT试验研究[J].岩土力学,2015,36(6):1591-1597. |
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| 作者姓名： | 王传洋 杨春和 衡 帅 冒海军 |
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| 作者单位： | 1. 中国科学院武汉岩土力学研究所 岩土力学与工程国家重点实验室，湖北 武汉430071； 2. 重庆大学 煤矿灾害动力学与控制国家重点实验室，重庆 400044 |
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| 基金项目： | 国家自然科学基金资助项目(No.51104144)；国家重点基础研究发展计划（973计划）(No.2010CB226701)。 |
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| 摘 要： | 裂缝的演化与空间展布规律是影响泥岩盖层密闭效果的关键因素。为研究泥岩失稳破坏过程中裂纹的萌生、扩展和汇集贯通等演化规律,针对龙马溪组泥岩进行了单轴压缩下的同步CT扫描试验,通过裂纹面积的变化特征及裂纹结构的分形特性,探讨了不同加载水平下裂纹的演化规律,从细观尺度揭示了泥岩裂纹演化与宏观变形特性的关系。研究结果表明:泥岩CT图像灰度频率及裂纹面积的变化均可反映裂纹的演化特征。荷载水平(即当前荷载与峰值荷载之比)为0~20%时,裂纹面积迅速增加,裂纹开始萌生,但由于受到闭合效应的抑制,相对并不活跃;荷载水平(当前荷载与峰值荷载之比)为20%~65%时,裂纹面积变化不大,裂纹萌生效应和闭合效应同时进行,且作用大致相抵,泥岩进入稳定承压阶段;荷载水平为65%~85%时,裂纹面积陡然增加,裂纹进入扩展及汇集贯通阶段,而荷载水平为65%时的突然跳跃,表明裂纹从萌生闭合到扩展过渡具有突发性和瞬时性。随着荷载的继续增加,泥岩内部结构呈复杂化、混乱化的变化趋势,且裂纹从外向内逐渐贯通。裂纹分形维数呈现的增长―下降―再增长―再下降的波状变化规律,是裂纹萌生、闭合、扩展和归并等相互转化的结果。
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| 关 键 词： | 泥岩 裂缝演化 CT扫描 裂纹面积 分形维数 |
| 收稿时间： | 2014-01-20 |
CT test for evolution of mudstone fractures under compressive load |
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| WANG Chuan-yang,YANG Chun-he,HENG Shuai,MAO Hai-jun.CT test for evolution of mudstone fractures under compressive load[J].Rock and Soil Mechanics,2015,36(6):1591-1597. |
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| Authors: | WANG Chuan-yang YANG Chun-he HENG Shuai MAO Hai-jun |
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| Institution: | 1. State Key Laboratory of Geomechanics and Geotechnical Engineering, Institute of Rock and Soil Mechanics, Chinese Academy of Sciences, Wuhan, Hubei 430071, China; 2. State Key Laboratory for Coal Mine Disaster Dynamics and Control, Chongqing University, Chongqing 400044, China |
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| Abstract: | The evolution and spatial distribution of fractures are key factors in the sealability of mudstone caprock. To investigate the evolution of crack initiation, propagation, coalescence during the process of deformation and failure for mudstone, uniaxial compression test and real-time CT scanning have been carried out for mudstone specimens of Longmaxi Formation. The crack evolution under different load levels is discussed; and the relationship between crack evolution and macroscopic deformation is revealed from the mesoscopic scale based on the variations of crack area and fractal characteristics of crack structure. The results show that: the evolution of mudstone cracks can be reflected with the changes of grey frequency and crack area. When the load applied on the specimen is at a level of 0-20%, even though crack area increases rapidly, crack initiation is not active due to the closing effect of cracks in compression process. When the load reaches a level of 20%-65%, crack area changes little owing to the generating effect and closing effect of cracks contributing equally; thus mudstone is in a stable stage. When the load is up to a level of 65%-85%, crack area increases sharply as the uniaxial effect of crack extension and coalescence speeds up. The sudden increase of crack area at the load level of 65% exhibits the burstiness and instantaneity of crack transformation from initiation, closing to extension. The complicated and disordered internal structures and cracks evolving from specimen surface to interior are clearly observed with the further increase of load. The curve of crack fractal dimension appears the “up―down―up―down” trend, which shows the evolution of initiation, closure, extension and coalescence of cracks. |
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| Keywords: | mudstone crack evolution CT scanning crack area fractal dimension |
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