| 应力比影响下的破裂角、闭锁角、摩擦系数及其耦合关系 |
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| 引用本文： | 关成尧,漆家福,邱楠生,赵国春,杨桥,白相东,李春雷.应力比影响下的破裂角、闭锁角、摩擦系数及其耦合关系[J].岩土力学,2012,33(12):3570-3576. |
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| 作者姓名： | 关成尧 漆家福 邱楠生 赵国春 杨桥 白相东 李春雷 |
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| 作者单位： | 1.中国石油大学（北京）油气资源与探测国家重点实验室，北京 102249；2.中国地质大学（北京） 地球科学与资源学院，北京 100083； 3.防灾科技学院，河北 三河 065201；4.中国石油勘探开发研究院 亚太研究所，北京 100083 |
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| 基金项目： | 国家十二五重大专项(No.2011ZX05025-005)支持 |
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| 摘 要： | 裂纹扩展和摩擦系数分属两个学科而鲜有联系，摩擦系数理论较少，主要依赖实验获得。在Griffith椭圆形裂纹基础上讨论摩擦面状裂纹力学模型，计算了单轴、三轴压应力情况下微裂纹扩展的期望方向及应力集中，那些方向偏离宏观破裂方向较大角度的裂纹因闭锁而无法延伸，应力比 越大，可扩展的微裂纹越向宏观裂纹面方向集中，随着围压 的增加，闭锁范围增大，实现了裂纹张性向剪性的转变。摩擦系数、方向集中度、应力比呈耦合关系，一方面，摩擦系数越大越利于微裂纹方向集中；另一方面微裂纹的方向集中导致了宏观裂纹面（裂缝）上凸起角度降低，进而减小摩擦系数。围压和裂纹扩展期的应力状况是影响摩擦系数的重要因素， 往往成为裂纹扩展的应力条件，凸起斜面摩擦系数越大，临界应力比越小。裂纹粗糙度(或分维数)对形成期的应力状况具有一定记忆功能。
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| 关 键 词： | 裂纹闭锁 压剪破裂 闭锁角 裂纹方向集中度 摩擦系数 应力比 耦合 |
| 收稿时间： | 2012-08-07 |
Crack angle,lock angle,friction coefficient under stress ratio affection and their coupling relationship in a compression-shear crack |
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| GUAN Cheng-yao,QI Jia-fu,QIU Nan-sheng,ZHAO Guo-chun,YANG Qiao,BAI Xiang-dong,LI Chun-lei.Crack angle,lock angle,friction coefficient under stress ratio affection and their coupling relationship in a compression-shear crack[J].Rock and Soil Mechanics,2012,33(12):3570-3576. |
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| Authors: | GUAN Cheng-yao QI Jia-fu QIU Nan-sheng ZHAO Guo-chun YANG Qiao BAI Xiang-dong LI Chun-lei |
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| Institution: | 1. State Key Laboratory of Petroleum Resources and Prospecting, China University of Petroleum, Beijing 102249, China; 2. School of Geosciences and Resources, China University of Geosciences, Beijing 100083, China; 3. Institute of Disaster Prevention Science and Technology, Sanhe, Hebei 065201, China; 4. Department of Asia-Pacific E＆P, Research Institute of Petroleum Exploration ＆ Development, Beijing 100083, China |
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| Abstract: | Cracks propagation and the friction coefficient belong to different research objectives and were seldom connected. The friction coefficient often come from experiments and lacked describing theoretically. Based on ‘Griffith ellipse cracks’, a ‘Griffith face cracks’ model which links the compression shear rupturing and microcrack friction is discussed. The macroscopic slit expectation, force ,stress concentration that under uniaxial stress and three-axial stress situations is calculated. Because of locking, only cracks near the crack angle can extend. Larger stress ratio ( ) means smaller direction concentration ratio. The lock angle were increased with the increase of or confining pressure. Those tension cracks can not develop and transform into compression-shear cracks mode. Those convex-concave are from direction discrete of microcracks become the inclination angle of the asperities in a surface and affect the friction coefficient. The friction coefficient, direction concentration ratio and the stress ratio is a coupling relationship; on the one hand, large friction coefficient helps the direction concentrati, on the other hand, the direction concentration leads to the decrease of the average angle of asperities which in a macroscopic crack and decrease the friction coefficient furthermore. The coupling model reveals that the ambient pressure and stress is an important controlling factor of the friction coefficient. The stress ratio is often the conditions that allow the cracks developing. The friction coefficient were inversely proportional to the critical stress ratio. The average inclination angle of surface asperities and fractal dimensions of macrocracks have some memory function with respect to the stress condition and may thus be useful in characterizing the paleo-stress field. |
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| Keywords: | crack lock compression-shear crack lock angle direction concentration ratio friction coefficient stress ratio coupling |
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