单轴压缩土样剪切带内、外主应变轴偏转角统计分析

doi:10.6038/pg2019BB0577

摘要/Abstract

摘要：

根据单轴压缩低液限黏土试样纵向应变较高时清晰剪切带内最大剪切应变(由数字图像相关方法获得)高值点位置布置曲折测线,并在曲折测线两侧布置平直测线,对测线上主应变轴偏转角和最大剪切应变进行了统计分析.研究发现,随着纵向应变的增加,对于根据左旋剪切带布置的曲折测线,主应变轴偏转角正值(逆时针偏转)所占比例呈增加趋势或保持不变,对于根据右旋剪切带布置的曲折测线,主应变轴偏转角正值所占比例呈减小趋势;对于根据左旋剪切带布置的平直测线,主应变轴偏转角正值所占比例呈减小趋势,对于根据右旋剪切带布置的平直测线,主应变轴偏转角正值所占比例呈增加趋势;当微裂纹刚出现时,右旋剪切带内主应变轴偏转角以负值(顺时针偏转)为主,而左旋剪切带内主应变轴偏转角以正值为主,剪切带两侧附近大部分区域主应变轴偏转方向与剪切带内的相反;剪切带内主应变轴偏转角的高峰和低谷通常与最大剪切应变的高峰或低谷对应或相邻;当较清晰剪切带出现后,剪切带外主应变轴正在偏转方向与剪切带内主应变轴偏转总量方向通常相反.

关键词: 土样, 剪切带, 最大剪切应变, 曲折测线, 主应变轴偏转角

Abstract:

Statistical analyses of maximum shear strains obtained by use of the digital image correlation method and principal strain axis rotational angles are conducted for low liquid limit clay specimens in uniaxial compression. Some curved monitored lines are arranged according to higher maximum shear strain positions in apparent shear bands at higher longitudinal strains, and some straight monitored lines are arranged at both sides of curved monitored lines. The following results are found. With an increase of the longitudinal strain, the percentage of positive values (anticlockwise rotation) of principal strain axis rotational angles shows an increasing or invariable trend for straight monitored lines arranged by sinistral shear bands, while it shows a decreasing trend for curved monitored lines arranged by dextral shear bands. The percentage of positive values of principal strain axis rotational angles shows a decreasing trend for straight monitored lines arranged by sinistral shear bands, while it shows an increasing trend for curved monitored lines arranged by dextral shear bands. When microcracks just occur, most of principal strain axis rotational angles for dextral shear bands are negative (clockwise rotation), most of principal strain axis rotational angles for sinistral shear bands are positive, and principal strain axis rotational angles near shear bands are usually opposite to those in shear bands. Positions of higher and lower values of principal strain axis rotational angles are consistent with or adjacent to those of higher or lower of maximum shear strains. Once an apparent shear band occurs, current rotational directions of principal strain axes outside the shear band are usually opposite to total rotational directions of principal strain axes in the shear band.

Key words: Clay specimen, Shear band, Maximum shear strain, Curved monitored line, Principal strain axis rotational angle

中图分类号:

P631

王学滨, 冯威武, 曹思雯, 杨梅, 侯文腾, 张博闻. 2019. 单轴压缩土样剪切带内、外主应变轴偏转角统计分析. 地球物理学进展, 34(1): 387-394. doi: 10.6038/pg2019BB0577.

WANG Xue-bin, FENG Wei-wu, CAO Si-wen, YANG Mei, HOU Wen-teng, ZHANG Bo-wen. 2019. Statistical analyses of principal strain axis rotational angles in shear bands and outside for clay specimens in uniaxial compression. Progress in Geophysics. 34(1): 387-394. doi: 10.6038/pg2019BB0577.

图/表 14

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参考文献 31

[1]	Cheng E L, Li G F, Chen H C . 1982. On the direction of the maximum compressive principal stress before and after the 1976 Songpan-Pingwu earthquake (M=7.2) of the sichuan province[J]. Acta Seismologica Sinica (in Chinese), 4(2):136-148.
[2]	Du Y Z, Wang X B . 2012. Digital image correlation method based on Newton-Raphson method and particle swarm optimization algorithm[J]. Computer Engineering and Applications (in Chinese), 48(34):184-189.
[3]	Gu H D, Chen Y T, Gao X L , et al. 1976. Focal mechanism of Haicheng, Liaoning province, earthquake of february 4, 1975[J]. Chinese Journal of Geophysics (in Chinese), 19(4):270-285.
[4]	Gu L, Wang X B, Du Y Z , et al. 2016. Experimental studies of rotation angles of principal strain axes for wet sandy soil specimens under uniaxial compression[J]. Rock and Soil Mechanics (in Chinese), 37(4):1013-1022.
[5]	Guo L L . 2013. Observations and analyses to transient processes of unstable slip on the fault by laboratory experiments(in Chinese) [Ph.D.thesis]. Beijing: Institute of Geology, China Earthquake Administration.
[6]	Li Y Z, Huang T, Dai B L . 2011. Research progresses on compaction bands in porous rocks[J]. Progress in Geophysics (in Chinese), 26(1):349-356.
[7]	Liu L Q, Ma J, Ma S L . 1995. Characteristics and evolution of background strain field on typical structure models[J]. Seismology and Geology (in Chinese), 17(4):349-356.
[8]	Liu L Q, Ma J, Wu X Q . 1986. An experimental study on the process of deformation and instability for en-enchelon faults[J]. Acta Seismologica Sinica (in Chinese), 8(4):393-403.
[9]	Ma J, Liu L Q, Ma S L . 1999. Fault geometry and departure of precursors from epicenter[J]. Earthquake Research in China (in Chinese), 15(2):106-115.
[10]	Rudnicki J W . 2004. Shear and compaction band formation on an elliptic yield cap[J]. Journal of Geophysical Research, 109(B3):B03402. doi: 10.1029/2003JB002633
[11]	Wang X B, Feng W W, Du Y Z , et al. 2016. Distributions of principal strain axis rotational angles at shear bands of soil specimens in uniaxial compression and statistical analyses[J]. Journal of Disaster Prevention and Mitigation Engineering (in Chinese), 36(6):853-860.
[12]	Wang X B, Hou W T, Zhang B W , et al. 2018. Statistical analyses of variation coefficients of three kinds of strains of coal specimens in uniaxial compression[J]. Progress in Geophysics (in Chinese), 33(4):1713-1720, doi: 10.6038/pg2018BB0303.
[13]	Xi D Y, Xu S L. 2015. Constitutive theory of porous rocks and soil material(in Chinese) [M]. Hefei: University of Science and Technology of China Press, 264-267.
[14]	Yu J L, Sun X, Yu Y Z , et al. 2010. Experimental study of the evolution of shear bands in structured soil[J]. Journal of Tsinghua University (Science and Technology)(in Chinese), 50(3):367-371.
[15]	Yu Y Z, Yu J L, Zhang B Y , et al. 2010. Analysis of the evolution of shear bands considering stress concentrations and redistribution around the tip[J]. Journal of Tsinghua University (Science and Technology) (in Chinese), 50(3):372-375.
[16]	Zhao S P, Feng Z J, Kong X Y , et al. 1999. Anomalous characteristics of stress and strain for the M_S 5.2 Cangshan earthquake[J]. Journal of Seismological Research (in Chinese), 22(1):38-41.
[17]	成尔林, 李桂芳, 陈和川 . 1982. 1976年四川省松潘-平武7.2级地震前后主压应力轴的方向特征[J]. 地震学报, 4(2):136-148.
[18]	杜亚志, 王学滨 . 2012. 基于Newton-Raphson迭代与PSO数字图像相关方法[J]. 计算机工程与应用, 48(34):184-189. doi: 10.3778/j.issn.1002-8331.1105-0229
[19]	顾浩鼎, 陈运泰, 高祥林 , 等. 1976. 1975年2月4日辽宁省海城地震的震源机制[J]. 地球物理学报, 19(4):270-285.
[20]	顾路, 王学滨, 杜亚志 , 等. 2016. 单轴压缩湿砂土试样主应变轴偏转规律试验研究[J]. 岩土力学, 37(4):1013-1022. doi: 10.16285/j.rsm.2016.04.014
[21]	郭玲莉 . 2013. 断层失稳滑动瞬态过程的实验观测与分析[博士论文]. 北京: 中国地震局地质研究所. doi: 10.3969/j.issn.0235-4975.2014.07.011
[22]	李云祯, 黄涛, 戴本林 . 2011. 高孔岩石局部压缩变形研究新进展[J]. 地球物理学进展, 26(1):349-356, doi: 10.3969/j.issn.1004-2903.2011.01.042. doi: 10.3969/j.issn.1004-2903.2011.01.042
[23]	刘力强, 马瑾, 马胜利 . 1995. 典型构造背景应变场特征及其演化趋势[J]. 地震地质, 17(4):349-356. doi: 10.1007/BF02006258
[24]	刘力强, 马瑾, 吴秀泉 . 1986. 雁列式断层变形与失稳过程的实验研究[J]. 地震学报, 8(4):393-403.
[25]	马瑾, 刘力强, 马胜利 . 1999. 断层几何与前兆偏离[J]. 中国地震, 15(2):106-115.
[26]	王学滨, 冯威武, 杜亚志 , 等. 2016. 单轴压缩土样剪切带上主应变轴偏转角的分布及规律统计[J]. 防灾减灾工程学报, 36(6):853-860.
[27]	王学滨, 侯文腾, 张博闻 , 等. 2018. 单轴压缩煤样三种应变的变异系数的统计分析[J]. 地球物理学进展, 33(4):1713-1720, doi: 10.6038/pg2018BB0303.
[28]	席道瑛, 徐松林 . 2015. 多孔岩土材料的本构理论[M]. 合肥: 中国科学技术大学出版社, 264-267.
[29]	喻葭临, 孙逊, 于玉贞 , 等. 2010. 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), 50(3):367-371.
[30]	于玉贞, 喻葭临, 张丙印 , 等. 2010. 考虑尖端应力集中和重分布的剪切带扩展分析[J]. 清华大学学报(自然科学版), 50(3):372-375.
[31]	赵淑萍, 冯志军, 孔向阳 , 等. 1999. 苍山M_S 5.2级地震应力应变异常特性[J]. 地震研究, 22(1):38-41.

编号	含水率 /%	孔隙比	湿密度 /(×10³ kg/m³)	高度×宽度×厚度 /(cm×cm×cm)
^#4	14.4	0.59	2.09	8.9×5.0×3.7
^#8	13.8	0.64	2.06	8.9×5.0×3.8
^#28	16.7	0.59	2.01	8.9×5.1×3.8
^#30	17.3	0.65	2.01	8.9×5.0×3.8

测线编号	纵向应变ε_a
测线编号	0.04	0.08	0.12	0.15	0.18
测线B₀	0.0134	0.0335	0.0573	0.0947	0.0954
测线B₁	0.0101	0.0137	0.0170	0.0230	0.0316
测线B₂	0.0096	0.0187	0.0356	0.0575	0.0641

测线编号	纵向应变ε_a
测线编号	0.07	0.10	0.13	0.17	0.21
测线C₀	0.0166	0.0158	0.0218	0.0385	0.0718
测线C₁	0.0148	0.0187	0.0292	0.0539	0.0680
测线C₂	0.0146	0.0149	0.0215	0.0412	0.0567

土样编号	测线编号	β₃标准差σ/(°)
土样编号	测线编号	时刻1	时刻2	时刻3	时刻4	时刻5
^#4	A₀	4.08	1.96	1.77	1.34	1.63
	A₁	5.56	3.58	2.87	3.46	4.57
	A₂	6.37	4.46	2.40	2.96	4.31
^#8	B₀	2.33	2.20	2.31	2.15	2.55
	B₁	3.43	2.25	1.80	1.58	1.56
	B₂	3.28	3.45	3.46	3.52	3.79
^#28	C₀	4.53	2.48	1.80	1.50	1.71
	C₁	3.94	2.51	1.80	1.44	1.13
	C₂	8.22	5.15	3.57	2.85	3.17
^#30	D₀	1.52	1.44	1.57	1.73	1.93
	D₁	1.26	1.59	1.90	2.13	2.33
	D₂	2.02	2.39	2.50	2.62	3.31

土样编号	测线编号	β₃的正值所占比例
土样编号	测线编号	时刻1	时刻2	时刻3	时刻4	时刻5
^#4	A₀	1	1	1	1	1
	A₁	0.56	0.67	0.69	0.64	0.62
	A₂	0.42	0.47	0.82	0.51	0.31
^#8	B₀	0.15	0.25	0.18	0	0
	B₁	0.25	0.27	0.23	0.27	0.42
	B₂	0.58	0.75	0.82	0.90	0.95
^#28	C₀	0.46	0.74	0.84	1	1
	C₁	0.39	0.30	0.23	0.11	0
	C₂	0.51	0.50	0.48	0.48	0.54
^#30	D₀	0.61	0.37	0.14	0.07	0.08
	D₁	0.93	0.85	0.90	0.90	0.95
	D₂	0.49	0.51	0.53	0.66	0.64