单轴压缩湿砂土试样主应变轴偏转规律试验研究
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摘要
利用自主开发的基于粒子群优化的数字图像相关方法,获得了单轴压缩湿砂土试样观测平面内主应变轴偏转角的时空分布规律。采用双三次样条插值方法,获取了任意位置的主应变轴偏转角,分析了土样将来出现剪切带位置、剪切带的中心及其尖端附近和剪切带外的主应变轴偏转角随纵向应变的演变规律。研究发现,随着纵向应变的增加,在土样观测平面内,主应变轴偏转角的范围由分散逐渐变得稳定,大部分区域最终分布在-10°~10°之间。当出现较清晰的剪切带以后(硬化阶段后期),剪切带内不同位置处主应变轴偏转角基本趋于恒定或稍有下降,大致稳定在-5°~5°之间,这与剪切带外的点的主应变轴偏转角均处于发展之中不同;而在剪切带尖端附近的点,主应变轴偏转角随纵向应变的演变规律比较复杂。
Using the self-developed digital image correlation method based on the particle swarm optimization algorithm, the spatiotemporal distributions of rotation angles of principal strain axes for wet sandy soil specimens are investigated under uniaxial compression. Using the bicubic spline interpolation, the rotation angles of principal strain axes at any positions are obtained to study the evolution of the rotation angles of principal strain axes with the longitudinal strains before the occurrence of a shear band, at its center, in the vicinity and at both sides of the band. It is found that with the increase of longitudinal strain, the rotation angles of principal strain axes change from a scattered distribution to a stable one; and at last, its range in most regions is-10°-10°. After the occurrence of an apparent shear band at the late stage of strain-hardening, at the center of the band, the rotation angles of principal strain axes tend to be stable or descend slightly, within a range of-5°-5°, while those at both sides of the band still increase. At tip of the band, the evolution of the rotation angles of principal strain axes is complex.
Using the self-developed digital image correlation method based on the particle swarm optimization algorithm, the spatiotemporal distributions of rotation angles of principal strain axes for wet sandy soil specimens are investigated under uniaxial compression. Using the bicubic spline interpolation, the rotation angles of principal strain axes at any positions are obtained to study the evolution of the rotation angles of principal strain axes with the longitudinal strains before the occurrence of a shear band, at its center, in the vicinity and at both sides of the band. It is found that with the increase of longitudinal strain, the rotation angles of principal strain axes change from a scattered distribution to a stable one; and at last, its range in most regions is-10°-10°. After the occurrence of an apparent shear band at the late stage of strain-hardening, at the center of the band, the rotation angles of principal strain axes tend to be stable or descend slightly, within a range of-5°-5°, while those at both sides of the band still increase. At tip of the band, the evolution of the rotation angles of principal strain axes is complex.
引文
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[15]王学滨,杜亚志,潘一山.基于DIC粗-细搜索方法的单轴压缩砂样的应变分布及应变梯度的实验研究[J].岩土工程学报,2012,34(11):2050-2057.WANG Xue-bin,DU Ya-zhi,PAN Yi-shan.Experimental studies of strain distribution and strain gradients for sand specimens in uniaxial compression based on the digital image correlation with coarse-fine search method[J].Chinese Journal of Geotechnical Engineering,2012,34(11):2050-2057.
[16]王学滨,杜亚志,潘一山,等.基于数字图像相关方法的等应变率下不同含水率砂样剪切带观测[J].岩土力学,2015,36(3):625-632.WANG Xue-bin,DU Ya-zhi,PAN Yi-shan.Measurement of shear bands of sand specimens with different water contents under constant strain rate based on digital image correlation method[J].Rock and Soil Mechanics,2015,36(3):625-632.
[17]刘鸿文.材料力学[M].北京:高等教育出版社,2004.LIU Hong-wen.Mechanics of materials[M].Beijing:Higher Education Press,2004.
[18]金观昌.计算机辅助光学测量[M].北京:清华大学出版社,2007.JIN Guan-chang.Computer aided optical metrology[M].Beijing:Tsinghua University Press,2007.
[19]赵锡宏,张启辉.土的剪切带试验与数值分析[M].北京:机械工业出版社,2003.ZHAO Xi-hong,ZHANG Qi-hui.Experiment and numerical analyses of shear band for soil[M].Beijing:China Machine Press,2007.
[2]沈瑞福,王洪瑾,周克骥,等.动主应力旋转下砂土孔隙水压力发展及海床稳定性判断[J].岩土工程学报,1994,16(3):70-75.SHEN Rui-fu,WANG Hong-jin,ZHOU Ke-ji,et al.Building-up of pore water pressure under cyclic rotation of principal stress and evaluation of stability of seabed deposit[J].Chinese Journal of Geotechnical Engineering,1994,16(3):70-75.
[3]ISHIHARA K,TOWHATA K.Sand response to cyclic rotation of principal stress directions as induced by wave loads[J].Soils and Foundations,1983,23(4):11-26.
[4]SYMES M J,GENS A,HIGHT D W.Drained principal stress rotation in saturated sand[J].Geotechnique,1988,38(1):59-81.
[5]LADE P V.Elasto-plastic behavior of K0-consonidation clays in torsion shear tests[J].Soils and Foundations,1989,29(2):127-140.
[6]沈扬,周建,张金良,等.考虑主应力方向变化的原状黏土强度及超静孔压特性研究[J].岩土工程学报,2007,29(6):843-847.SHEN Yang,ZHOU Jian,ZHANG Jin-liang,et al.Research on strength and pore pressure of intact clay considering variation of principal stress direction[J].Chinese Journal of Geotechnical Engineering,2007,29(6):843-847.
[7]史宏彦,白琳.平面应变条件下土的非共轴变形特性[J].广东工业大学学报,2007,24(3):84-87.SHI Hong-yan,BAI Lin.Non-coaxial behavior of soil under plane strain conditions[J].Journal of Guangdong University of Technology,2007,24(3):84-87.
[8]PAPAMICHOS E,VARDOULAKIS I.Shear band formation in sand according to non-coaxial plasticity model[J].Geotechnique,1995,45(4):649-661.
[9]钱建固,黄茂松.土体变形分叉的非共轴理论[J].岩土工程学报,2004,26(6):777-781.QIAN Jian-gu,HUANG Mao-song.Non-coaxiality for deformation bifurcation in soils[J].Chinese Journal of Geotechnical Engineering,2004,26(6):777-781.
[10]张启辉,赵锡宏.主应力轴旋转对剪切带形成的影响分析[J].岩土力学,2000,21(1):32-35.ZHANG Qi-hui,ZHAO Xi-hong.An influence on shear band formation of the rotations of principal stress directions[J].Rock and Soil Mechanics,2000,21(1):32-35.
[11]喻葭临,孙逊,于玉贞,等.结构性土中剪切带扩展的模型试验研究[J].清华大学学报(自然科学版),2010,50(3):367-371.YU Jia-lin,SUN Xun,YU Yu-zhen,et al.Experimental study of the evolution of shear bands in structured soil[J].Journal of Tsinghua University(Science and Technology),2010,50(3):367-371.
[12]QIAN J G,HUANG M S,SUN H Z.Macro-micromechanical approaches for non-coaxiality of coarse grained soils[J].Science China(Technological Sciences),2011,54(Supp.1):147-153.
[13]宋义敏,赵同彬,姜耀东.基于DSCM的岩石蠕变变形场演化试验研究[J].中国矿业大学学报,2013,42(3):466-470.SONG Yi-min,ZHAO Tong-bin,JIANG Yao-dong.Experimental study on the evolution of creep deformation field of rock based on DSCM[J].Journal of China University of Mining&Technology,2013,42(3):466-470.
[14]李元海,靖洪文,朱合华,等.基于图像相关分析的土体剪切带识别方法[J].岩土力学,2007,28(3):522-526.LI Yuan-hai,JING Hong-wen,ZHU He-hua,et al.A technique of identifying shear band accurately in granular soil using image correlation analysis[J].Rock and Soil Mechanics,2007,28(3):522-526.
[15]王学滨,杜亚志,潘一山.基于DIC粗-细搜索方法的单轴压缩砂样的应变分布及应变梯度的实验研究[J].岩土工程学报,2012,34(11):2050-2057.WANG Xue-bin,DU Ya-zhi,PAN Yi-shan.Experimental studies of strain distribution and strain gradients for sand specimens in uniaxial compression based on the digital image correlation with coarse-fine search method[J].Chinese Journal of Geotechnical Engineering,2012,34(11):2050-2057.
[16]王学滨,杜亚志,潘一山,等.基于数字图像相关方法的等应变率下不同含水率砂样剪切带观测[J].岩土力学,2015,36(3):625-632.WANG Xue-bin,DU Ya-zhi,PAN Yi-shan.Measurement of shear bands of sand specimens with different water contents under constant strain rate based on digital image correlation method[J].Rock and Soil Mechanics,2015,36(3):625-632.
[17]刘鸿文.材料力学[M].北京:高等教育出版社,2004.LIU Hong-wen.Mechanics of materials[M].Beijing:Higher Education Press,2004.
[18]金观昌.计算机辅助光学测量[M].北京:清华大学出版社,2007.JIN Guan-chang.Computer aided optical metrology[M].Beijing:Tsinghua University Press,2007.
[19]赵锡宏,张启辉.土的剪切带试验与数值分析[M].北京:机械工业出版社,2003.ZHAO Xi-hong,ZHANG Qi-hui.Experiment and numerical analyses of shear band for soil[M].Beijing:China Machine Press,2007.