非均质脆岩受压破坏特征及裂纹扩展规律
Failure mechanism and fracture development law of heterogeneous brittle rock
-
摘要: 为研究非均质脆岩单轴压缩破裂特征及裂纹扩展规律，应用偏光显微镜得到了花岗岩的矿物成分及含量；通过室内试验得到花岗岩的基本力学参数；基于PFC2D软件和矿物组成，应用随机颗粒簇的方法构建了花岗岩数值试件，并通过参数反演得到细观参数，模拟结果与室内试验力学特性吻合；应用FISH语言编译相关程序监测了数值试件压缩过程中的裂纹扩展及声发射振铃计数。结果表明：花岗岩属于典型的非均质脆岩，单轴压缩应力应变曲线峰前无屈服阶段，峰后无残余阶段，达到应力峰值后瞬间爆裂；花岗岩受压呈劈裂破坏，破坏模式为拉、剪复合破坏，微破裂以拉裂纹为主，剪裂纹为辅，且拉裂纹的出现早于剪裂纹；声发射振铃数表明花岗岩受压初期已有少量损伤破坏出现，这是花岗岩矿物强度非均质的体现；大量损伤出现在近峰值部分，导致峰后微裂纹迅速贯通形成宏观断裂面，这也是峰后试件瞬间爆裂的主要原因。Abstract: To study the failure mode and fracture development of brittle rock under uniaxial compression, the mineral composition and content were tested through polarized microscope. The basic mechanical parameters of granite were obtained through laboratory tests. The numerical specimen of granite was built based on the PFC2D software and random particle cluster method. After parameter calibration, the simulation results coincide with the laboratory tests well. FISH programs were compiled to capture the crack development and acoustic emission events during the compression progress. The results show that granite is a typical heterogeneous brittle rock, which has no yielding stage before peak and has no residual stage after the peak. The main failure mode is splitting damage, both tensile and shear fractures show up in the specimen. Tensile cracks are the main crack type and appear earlier than the shear cracks. The acoustic emission events show that a small amount of damage appears during the initial compressive stage, which is manifestation of the heterogeneous mineral strength. Plenty of damages appear before the peak, which results in the quick coalescence of micro-cracks and forms macro-failure fracture. This is the main reason for the instant burst of the granite after peak stress.
-
Keywords:
- heterogeneous /
- brittle rock /
- compression failure /
- fracture propagation /
- discrete element
-
-
[1] Tang C A, Liu H, Lee P K K, et al. Numerical studies of the influence of microstructure on rock failure in uniaxial compression - Part I: effect of homogeneity[J]. International Journal of Rock Mechanics and Mining Engineering, 2000, 37（4）: 555-569. [2] Tang C A, Tham L G, Wang S H, et al. A numerical study of the influence of homogeneity on the strength characterization of rock under uniaxial tension[J]. Mechanics of Matreials, 2007, 39（4）: 326-339. [3] Xu T, Tang C A, Zhao J, et al. Modelling the time-dependent rheological behaviour of heterogeneous brittle rocks[J]. Geophysical Journal International, 2012, 189（3）: 1781-1796. [4] 陈永强，郑小平，姚振汉．三维非均匀脆性材料破坏过程的数值模拟[J]．力学学报，2002，34（3）：351－361. CHEN Yongqiang, ZHENG Xiaoping, YAO Zhenhan. Numerical simulation of failure processes in 3D heterogeneous brittle material[J]. Acta Mechanica Sinica, 2002, 34（3）: 351-361.
[5] Feng X T, Pan P Z, Zhou H. Simulation of the rock microfracturing process under uniaxial compression using an elasto-plastic cellular automaton[J]. International Journal of Rock Mechanics and Mining Engineering, 2006, 43（7）: 1091-1108. [6] Li M T, Feng X T, Zhou H. 2D vector cellular automata model for simulating fracture of rock under tensile condition[J]. Key Engineering Materials, 2004, 261-263: 705-710. [7] 王学滨．含随机材料缺陷岩样的破坏前兆及剪切带模拟[J]．地下空间与工程学报，2007，3（6）：1047－1050. WANG Xuebin. Numerical simulation of failure precursor and shear bands for rock specimens with random material imperfections[J]. Chinese Journal of Underground Space and Engineering, 2007, 3（6）: 1047-1050.
[8] 王学滨．具有初始随机材料缺陷的矿柱渐进破坏模拟[J]．中国矿业大学学报，2008，37（2）：196－200. WANG Xuebin. Numerical simulation of progressive failure in mine pillars having initially random material imperfections[J]. Journal of Chinese University of Mining & Technology, 2008, 37（2）: 196-200.
[9] Tang X W, Zhou Y D, Zhang C H, et al. Study on the homogeneity of concrete and its failure behavior using the equivalent probabilistic model[J]. Journal of Materials in Civil Engineering, 2011, 23（4）: 402-413. [10] Manoucherian A, Cai M. Influence of material homogeneity on failure intensity in unstable rock failure[J]. Computers and Geotechnics, 2016, 71: 237-246. [11] Peng J, Wong L N Y, Teh C I. Influence of grain size homogeneity on strength and micro-cracking behavior of crystalline rocks[J]. Journal of Geophysical Research: Solid Earth, 2017, 122（2）: 1054-1073. [12] Wong L N Y, Zhang Y H. An extended grain-based model for characterizing crystalline materials: an example of marble[J]. Advanced Theory and Simulations, 2018, 1800039: 1-14. [13] Liu G, Cai M, Huang M. Mechanical properties of brittle rock governed by micro-geometric homogeneity[J]. Computers and Geotechnics, 2018, 104: 358-372. [14] Lan H X, Martin C D, Hu B. Effect of homogeneity of brittle rock on micromechanical extensile behavior during compression loading[J]. Journal of Geophysical Research, 2010, 115: B0102. [15] Chen W, Konietzky H. Simulation of homogeneity, creep, damage and lifetime for loaded brittle rocks[J]. Tectonophysics, 2014, 633: 164-175. [16] Chen W, Konietzky H, Abbas S M. Numerical simulation of time-independent and -dependent fracturing in sandstone[J]. Engineering Geology, 2015, 193: 118. [17] Chen W, Li X, Konietzky H. Numerical simulation of lifetime and time-dependent damage for granite by continuous and discontinuous approaches[J]. Environmental Earth Sciences, 2018, 77（16）: 594. [18] Nicksiar M, Martin C D. Factors affecting crack initiation in low porosity crystalline rocks[J]. Rock Mechanics and Rock Engineering, 2014, 47（4）: 1165-1181. [19] Gao F Q, Stead D, Elmo D. Numerical simulation of microstructure of brittle rock using a grain-breakable distinct element grain-based model[J]. Computers and Geotechnics, 2016, 78: 203-217. [20] 马文强，王振慧．均质度对脆岩压缩破坏及裂纹扩展的影响规律[J]．信阳师范学院学报（自然科学版），2020，33（4）：689. MA Wenqiang, WANG Zhenhui. Influences of failure features and fracture development on homogeneity coefficient of brittle rock[J]. Journal of Xinyang Normal University（Natural Science Edition）, 2020, 33（4）: 689.
计量
- 文章访问数: 30
- HTML全文浏览量: 0
- PDF下载量: 12
下载:
