INFLUENCE OF STRENGTH PARAMETERS ON OVERALL DEFORMATIONS OF ROCK SPECIMENS WITH INITIALLY RANDOM MATERIAL IMPERFECTIONS
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摘要: 在单轴平面应变压缩条件下, 采用FLAC模拟了初始内聚力及内摩擦角对具有随机材料缺陷岩样轴向、侧向、体积变形及由侧向应变及轴向应变计算得到的泊松比的演变的影响。采用编写的FISH函数于试样内部规定随机缺陷并计算其全部变形特征。密实的岩石服从莫尔库仑剪破坏与拉破坏复合的破坏准则, 破坏之后呈现应变软化—理想塑性行为。随着强度参数(初始内聚力及内摩擦角)的增加, 应力峰值及对应的侧向应变的值提高, 体积应变的峰值增加, 应力峰值所对应的计算得到的泊松比稍有增加。由于被剪切带所分割的毗邻块体之间的相对滑动, 纵然扩容角为零, 试样在峰后的变形阶段, 仍然可以观察到体积膨胀现象, 这与作者的理论分析结果一致。当强度参数降低时, 侧向应变—轴向应变曲线、体积应变—轴向应变曲线及计算得到的泊松比—轴向应变曲线的峰前非线性部分变得短暂。剪切带倾角的数值解的上限低于Coulomb理论, 下限在Roscoe理论附近波动, Arthur理论的预测结果与本文剪切带倾角的数值解更接近.Abstract: For heterogeneous rock specimen with smooth ends and initially random material imperfections in uniaxial plane strain compression, the effects of initial cohesion and internal friction angle on the overall deformational characteristics (such as the axial, lateral and volumetric strains as well as the calculated Poisson's ratios) are modeled using FLAC. A few written FISH functions are used to set the random imperfections and to calculate the overall deformational characteristics. For intact rock, the failure criterion is a combined Mohr-Coulomb criterion with tension cut-off, exhibiting linear strain-softening and then ideal plastic behavior beyond the occurrence of failure. Imperfection undergoes ideal plastic behavior beyond the occurrence of failure. As strength parameters (such as initial cohesion and internal friction angle) increase, the peak stress and related lateral strain increase, and the peak volumetric strain increases also, and the calculated Poisson's ratio corresponding to the peak stress increases slightly. At post-deformational stage, the volume of the specimen can dilate although the dilation angle is zero, as is in agreement with the analytical solution proposed by Wang (2006). This is attributable to the relative sliding between adjacent rock blocks separated by shear zones. With lower strength parameters, the nonlinear pre-peak portions of lateral strain-axial strain curve, volumetric strain-axial strain curve and calculated Poisson's ratio-axial strain curve become shorter. The numerically predicted upper bound of shear band inclination is lower than that predicted by Coulomb theory, and the lower bound approaches that predicted by Roscoe theory. The predicted results by Arthur theory are closer to the present numerical shear band inclination.
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Key words:
- cohesion /
- internal friction angle /
- lateral strain /
- volumetric strain /
- random imperfection /
- dilatancy
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图 2 不同强度参数时应力—轴向应变曲线
Figure 2. The stress-axial strain curves with different strength parameters
图 3 不同强度参数时应力—侧向应变曲线
Figure 3. The stress-lateral strain curves with different strength parameters
图 4 不同强度参数时侧向应变—轴向应变曲线
Figure 4. The lateral strain-axial strain curves with different strength parameters
图 5 不同强度参数时体积应变—轴向应变曲线
Figure 5. The volumetric strain-axial strain curves with different strength parameters
图 6 不同强度参数时计算得到的泊松比—轴向应变曲线
Figure 6. The calculated Poisson's ratio-axial strain curves with different strength parameters
图 7 不同强度参数时试样的最终破坏模式
Figure 7. The final failure modes of rock specimens with different strength parameters
图 8 不同强度参数时试样最终的变形后的剪切应变增量等值线图
Figure 8. The final deformed shear strain increment contour maps of final deformed rock specimens with different strength parameters
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[1] Vermeer P A.The orientation of shear bands in biaxial tests[J].Géotechnique, 1990, 40 (2):223 ~ 236. doi: 10.1680/geot.1990.40.2.223 [2] Vardoulakis I.Shear band inclination and shear modulus of sand in biaxial tests[J].International Journal for Numerical and Analytical Methods in Geomechanics, 1980, 4 (2):103 ~ 119. doi: 10.1002/(ISSN)1096-9853 [3] Tang C A, Kou S Q.Crack propagation and coalescence in brittle materials under compression[J].Engineering Fracture Mechanics, 1998, 61 (3 ~ 4):311 ~ 324. http://cn.bing.com/academic/profile?id=1f1eed49746cf8bb7273fb7bf154b945&encoded=0&v=paper_preview&mkt=zh-cn [4] Fang Z, Harrison J P.Development of a local degradation approach to the modeling of brittle fracture in heterogeneous rocks[J]. International Journal of Rock M echanics and Mining Sciences, 2002, 39 (4):443 ~ 457. doi: 10.1016/S1365-1609(02)00035-7 [5] 王学滨.初始内聚力及摩擦角对岩样全部变形特征的影响[J].沈阳建筑大学学报(自然科学版), 2005, 21 (5):472 ~ 477. http://d.old.wanfangdata.com.cn/Periodical/syjzgcxyxb200505011Wang Xue-bin.Effects of initial cohesions and friction angles on entire deformational characteristics of rock specimen[J].Journal of Shenyang Jianzhu University (Natural Science), 2005, 21 (5):472 ~ 477. http://d.old.wanfangdata.com.cn/Periodical/syjzgcxyxb200505011 [6] 王学滨.剪胀对岩样全部变形特征的影响[J].四川大学学报(工程科学版), 2005, 37 (5):25 ~ 30. http://d.old.wanfangdata.com.cn/Periodical/scdxxb-gckx200505006Wang Xue-bin.Effects of shear dilatancy on entire deformational characteristics of rock specimen[J].Journal of Sichuan University (Engineering Science Edition), 2005, 37 (5):25 ~ 30. http://d.old.wanfangdata.com.cn/Periodical/scdxxb-gckx200505006 [7] 王学滨.软化模量对岩样全部变形特征的影响[J].岩土工程学报, 2006, 28 (5):600 ~ 605. http://d.old.wanfangdata.com.cn/Periodical/ytgcxb200605010Wang Xue-bin.Effect of softening modulus on entire deformational characteristics of rock specimen[J].Chinese Journal of Geotechnical Engineering, 2006, 28 (5):600 ~ 605. http://d.old.wanfangdata.com.cn/Periodical/ytgcxb200605010 [8] 王学滨.材料缺陷对岩样变形局部化影响数值模拟[J].岩土力学, 2006, 27 (8):1241 ~ 1247. http://kns.cnki.net/KCMS/detail/detail.aspx?filename=ytlx200608002&dbname=CJFD&dbcode=CJFQWang Xue-bin.Numerical simulation of influence of material imperfection on strain localization[J].Rock and Soil M echanics, 2006, 27 (8):1241 ~ 1247. http://kns.cnki.net/KCMS/detail/detail.aspx?filename=ytlx200608002&dbname=CJFD&dbcode=CJFQ [9] Wang Xue-bin. Effect of end-restraint on failure process and stress-strain curve for geomaterial specimen with random material imperfections[A]. Proceedings of the International Workshop on Constitutive Modelling-Development, Implementation, Evaluation and Application[C]. Edited by Yin Jian-hua, Li Xiang-song, Yeung A T, et al. Hong Kong : Advanced Technovation Limited, 2007, 360 ~ 366. [10] 王学滨.应变软化扩容对含随机缺陷岩石的渐进变形及破坏前兆特征的影响[J].地质力学学报, 2008, 14 (2): 158 ~ 167. http://journal.geomech.ac.cn/ch/reader/view_abstract.aspx?flag=1&file_no=20080216&journal_id=dzlxxbWang Xue-bin.Effects of strain-softening dilatancy on progressive deformations and precursors to failure of rock with initial random imperfections[J].Journal of Geomechanics, 2008, 14 (2):158 ~ 167. http://journal.geomech.ac.cn/ch/reader/view_abstract.aspx?flag=1&file_no=20080216&journal_id=dzlxxb [11] 王学滨.平面应变压缩岩样侧向变形特征数值模拟[J].岩土工程学报, 2005, 27 (5):525 ~ 530. http://d.old.wanfangdata.com.cn/Periodical/ytgcxb200505008Wang Xue-bin.Numerical simulation of lateral deformation of rock specimen in plane strain compression[J].Chinese Journal of Geotechnical Engineering, 2005, 27 (5):525 ~ 530. http://d.old.wanfangdata.com.cn/Periodical/ytgcxb200505008 [12] Wang Xue-bin. Analytical solution of complete stress-strain curve in uniaxial compression based on gradient-dependent plasticity [A]. Eurock 2005-Impact of Human Activity on the Geological Environment[C]. Taylor & Francis Group, London, 2005, 661 ~ 667. [13] Wang X B.Prediction of height effect, plastic deformation and fracture energy for high-strength concrete by linear shear softening constitutive relation based on energy conservation method[J].M agzine of Concrete Research, 2007, 59 (5):341 ~ 350. doi: 10.1680/macr.2007.59.5.341 [14] 王学滨, 马剑, 刘杰, 等.基于梯度塑性本构理论的岩样侧向变形分析(I):基本理论及本构参数对侧向变形的影响[J].岩土力学, 2004, 25 (6):904 ~ 908. http://kns.cnki.net/KCMS/detail/detail.aspx?filename=ytlx200406016&dbname=CJFD&dbcode=CJFQWang Xue-bin, Ma Jian, Liu Jie et al.Analysis of lateral deformation of rock specimen based on gradient-dependent plasticity (I):basic theory and effect of constitutive parameters on lateral deformation[J].Rock and Soil Mechanics, 2004, 25 (6): 904 ~ 908. http://kns.cnki.net/KCMS/detail/detail.aspx?filename=ytlx200406016&dbname=CJFD&dbcode=CJFQ [15] Wang Xue-bin.Volume change of heterogeneous quasi-brittle materials in uniaxial compression[J].Journal of Wuhan University of Technology-Materials Science Edition, 2006, 21 (3):162 ~ 167. doi: 10.1007/BF02840909 [16] 王学滨.岩样单轴压缩峰后泊松比理论研究[J].工程力学, 2006, 23 (4):99 ~ 103. http://kns.cnki.net/KCMS/detail/detail.aspx?filename=gclx200604017&dbname=CJFD&dbcode=CJFQWang Xue-bin.Analysis of the post-peak Poisson's ratio of rock specimens in uniaxial compression[J].Engineering M echanics, 2006, 23 (4):99 ~ 103. http://kns.cnki.net/KCMS/detail/detail.aspx?filename=gclx200604017&dbname=CJFD&dbcode=CJFQ [17] Bardet J P.Orientation of shear bands in frictional soils[J].Journal of Engineering Mechanics, ASCE, 1991, 117 (7):1466 ~ 1484. doi: 10.1061/(ASCE)0733-9399(1991)117:7(1466) -
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