岩石中裂隙分布对岩石的宏-微观力学性质和微裂纹的发育演化规律具有重要的影响。通过离散元方法(DEM),采用光滑节理模型建立不同裂隙倾角的模型进行单轴压缩试验,详细研究了大理岩在压缩过程中应力-应变特征、微裂纹发育演化过程、微观尺度上的能量耗散分配机制。结果表明:裂隙倾角与模型的应力-应变具有相关性,也影响微裂纹的发育演化过程;当裂隙倾角较小时,在达到峰值强度之前就产生了可见的拉裂纹,达到峰值强度之后拉裂纹继续增长并出现其他宏观裂缝;裂隙倾角较大时,达到峰值强度之前所产生的微裂纹大多零星分布,达到峰值强度之后微裂纹快速增加,形成多条裂缝。能量耗散研究表明:岩石的能量主要通过颗粒黏结存储于弹性势能中;在压缩过程中,弹性势能会缓慢降低并转变为摩擦耗能、阻尼耗能及破裂耗能,而破坏时4种能量占比大致相当。研究成果可为揭示裂隙岩石在压缩作用下裂纹扩展的细观力学响应机制提供参考。
Abstract
The distribution of flaws in rock has evident influence on the macro-and-microscopic mechanical properties and the evolution of microcracks of rocks. The smooth joint model was adopted to establish the rock model with different inclination angles based on the discrete element method (DEM) for uniaxial compression test. The stress-strain characteristics, microcracks development, distribution of energy dissipation in microscopic scale in the process of compression are studied. Results imply that the inclination angle of flaw is correlated with the stress-strain of the model, and also affects the evolution of microcracks. When the inclination angle of flaw is small, visible tensile cracks develop before peak strength is reached, and the cracks continue to grow after peak strength and other macroscopic cracks appear. On the contrary, when the inclination angle of flaw is large, the microcracks are mostly scattered before the peak strength, and surged to multiple cracks after the peak strength. Energy dissipation rule shows that the energy of rock is mainly stored in elastic energy through parallel bond. In the process of compression, the elastic energy decreases slowly and turns into frictional energy, damping energy and fracture energy. The proportions of such four kinds of energy are roughly equal at failure.
关键词
大理岩 /
断续裂隙 /
裂纹演化 /
能量耗散 /
裂隙倾角
Key words
marble /
pre-existing flaw /
evolution of crack /
energy dissipation /
inclination angle of flaw
{{custom_sec.title}}
{{custom_sec.title}}
{{custom_sec.content}}
参考文献
[1] 张 平,李 宁,贺若兰,等.动载下两条断续预制裂隙贯通机制研究[J].岩石力学与工程学报,2006,25(6):1210-1217.
[2] WONG N Y. Crack Coalescence in Molded Gypsum and Carrara Marblea[D]. Massachusetts: Massachusetts Institute of Technology, 2008.
[3] BOBET A. Fracture Coalescence in Rock Materials: Experimental Observations and Numerical Predictions[D]. Massachusetts: Massachusetts Institute of Technology, 1983.
[4] 杨圣奇.断续三裂隙砂岩强度破坏和裂纹扩展特征研究[J].岩土力学,2013,34(1):31-39.
[5] YANG Z Y,CHEN J M,HUANG T H. Effect of Joint Sets on the Strength and Deformation of Rock Mass Models[J]. International Journal of Rock Mechanics and Mining Sciences, 1998, 35(1): 75-84.
[6] BOBET A, EINSTEIN H H. Fracture Coalescence in Rock-type Materials under Uniaxial and Biaxial Compression[J]. International Journal of Rock Mechanics and Mining Sciences, 1998, 35(7): 863-888.
[7] SAGONG M, BOBET A. Coalescence of Multiple Flaws in a Rock-model Material in Uniaxial Compression[J]. International Journal of Rock Mechanics and Mining Sciences, 2002, 39(2): 229-241.
[8] PARK C H, BOBET A. Crack Initiation, Propagation and Coalescence from Frictional Flaws in Uniaxial Compression[J]. Engineering Fracture Mechanics, 2010, 77(14): 2727-2748.
[9] WONG L N Y, EINSTEIN H H. Using High Speed Video Imaging in the Study of Cracking Processes in Rock[J]. Geotechnical Testing Journal, 2009, 32(2): 164-180.
[10]刘 宁,张春生,褚卫江.深埋大理岩破裂扩展时间效应的颗粒流模拟[J].岩石力学与工程学报,2011,30(10):1989-1996.
[11]黄 丹,李小青.基于微裂纹发育特性的大理岩特征强度数值模拟研究[J].岩土力学,2017,38(1):253-262.
[12]ZHANG X P,WONG L N Y. Cracking Processes in Rock-like Material Containing a Single Flaw under Uniaxial Compression:A Numerical Study Based on Parallel Bonded-particle Model Approach[J]. Rock Mechanics and Rock Engineering,2012,45(5):711-737.
[13]ZHANG X P,WONG L N Y. Crack Initiation,Propagation and Coalescence in Rock-like Material Containing Two Flaws:A Numerical Study Based on Bonded-particle Model Approach[J]. Rock Mechanics and Rock Engineering,2013,46(5):1001-1021.
[14]HUANG Dan, WANG Jian-feng, LIU Su. A Comprehensive Study on the Smooth Joint Model in DEM Simulation of Jointed Rock Masses[J]. Granular Matter,2015,17(6):775-791.
[15]褚卫江.深埋条件下隧洞围岩稳定与结构安全评价[D].杭州:中国水电顾问集团华东勘测设计院,2009.
[16]YANG Sheng-qi, JING Hong-wen. Strength Failure and Crack Coalescence Behavior of Brittel Sandstone Samples Containing a Single Fissure under Uniaxial Compression[J]. International Journal of Fracture, 2011, 168(2):227-250.
[17]周 博,黄润秋,汪华斌,等.基于离散元法的砂土破碎演化规律研究[J].岩土力学,2014,35(9):2709-2716.
[18]WANG Jian-feng, YAN Hai-bin. DEM Analysis of Energy Dissipation in Crushable Soils[J]. Soils and Foundations, 2012, 52(4): 644-657.
PDF(2251 KB)
