Experimental study on seismic subsidence characteristics of structural loess under cyclic torsional shear
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摘要: 原状结构性黄土具有显著的动力易损性。地震作用下黄土的骨架结构遭到破坏,使得土骨架结构的颗粒重新排列而变得致密,土的架空孔隙结构塌陷,孔隙体积减小,宏观上表现为黄土产生震陷变形。通过西安原状黄土在不同含水率、不同固结围压条件下的动扭剪试验,表明不同含水率筒状黄土试样的轴向变形非线性累积增长,径向和环向变形近似等于零。测试分析了黄土在动扭剪过程中孔隙结构塌陷的累积体应变表征震陷性的震陷系数,以及动剪应力幅值、振次、含水率及固结围压对黄土震陷系数的影响。揭示黄土的震陷系数随动剪应力幅值、循环振次、固结围压和含水率的增大而增加,建立了黄土震陷系数与动剪应力、振次、固结围压和含水率之间的关系式,提出了黄土震陷变形预测的一种途径。Abstract: The undisturbed loess has significant structural and dynamic vulnerability. Under the earthquake, the dynamic shearing action destroys the original structure of loess. The pore volume of loess is reduced and the soil particles are rearranged and compacted, and the macroscopic representation is the occurrence of loess response, which is called seismic deformation of loess. In this study, the dynamic torsional shear tests on Xi'an undisturbed loess are conducted under different water contents and confining pressures. The axial cumulative deformation of undisturbed loess under different experimental conditions is analyzed. The influence of dynamic shear stress amplitude, vibration frequency, water content and consolidation confining pressure on the seismic subsidence deformation of loess is discussed. In addition, the empirical formula for calculating the seismic subsidence deformation of loess is established on the basis of influencing factors. The results show that the seismic subsidence deformation of loess increases gradually with the action of dynamic shear stress, and the growth rate tends to decline. The water content and consolidation confining pressure are the important factors on the seismic subsidence deformation characteristics of undisturbed loess. Under the same dynamic shear stress, the seismic subsidence deformation increases with the increase of water content and decreases with the increase of consolidated confining pressure. And the empirical formula for the seismic subsidence deformation of loess can be used to calculate the seismic deformation of loess foundation.
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图 1 空心圆柱试样的加载和应力条件
Figure 1. Loading and stress conditions of hollow cylinder specimen
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图 3 扭剪仪内外腔压差测试原理图
Figure 3. Schematic diagram of measuring pressure difference between inner and outer chambers of torsional shear instrument
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图 4 内、外腔水位变化时程曲线
Figure 4. Time-history curve of water level change in inner and outer chambers
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图 6 含水率12%黄土的震陷曲线
Figure 6. Seismic curves of loess under different vibration times (water content of 12%)
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图 7 不同含水率条件下黄土的震陷曲线
Figure 7. Curves of seismic subsidence of loess under different water contents
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图 8 不同固结围压条件下黄土的震陷曲线
Figure 8. Curves of seismic subsidence of loess under different confining pressures
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图 9 不同影响因素与黄土的震陷系数的关系
Figure 9. Relationship between different influencing factors and seismic subsidence coefficient of loess
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[1] 谢定义. 黄土土力学[M]. 北京: 高等教育出版社, 2015. XIE Ding-yi. Mechanics of Loess[M]. Beijing: Higher Education Press, 2015. (in Chinese)
[2] 刘祖典. 黄土力学与工程[M]. 西安: 陕西科技出版社, 1997. LIU Zu-dian. Mechanics and Engineering of Loess[M]. Xi'an: Shaanxi Science& Technology Press, 1997. (in Chinese)
[3] 刘东生. 黄土与环境[M]. 北京: 科学出版社, 1985: 208-247. LIU Dong-sheng. Loess and the Environment[M]. Beijing: China Science Press, 1985: 208-247. (in Chinese)
[4] 邵生俊. 砂土的物态本构模型及其应用[M]. 西安: 陕西科技出版社, 2002. SHAO Sheng-jun. Physical State Constitutive Model of Sand and Application[M]. Xi'an: Shaanxi Science& Technology Press, 2002. (in Chinese)
[5] 王强. 黄土的震陷特性及场地震陷分析评价方法研究[D]. 西安: 西安理工大学, 2017. WANG Qiang. Seismic Subsidence Characteristic of Loess and Evaluation Methods of Seismic Subsidence At Loess Site[D]. Xi'an: Xi'an University of Technology, 2017. (in Chinese)
[6] 王兰民. 黄土动力学[M]. 北京: 地震出版社, 2003. WANG Lan-min. Loess Dynamics[M]. Beijing: Earthquake Publishing House, 2003. (in Chinese)
[7] 张帅. 双向循环应力作用下黄土强度特性试验研究[D]. 陕西: 西北农林科技大学, 2014. ZHANG Shuai. Experiment Research on Strength Character of Loess Under Bi-Directional Cyclic Loding[D]. Shaanxi: Xi'an University of Technology, 2014. (in Chinese)
[8] 吴飞洁. 非饱和黄土震陷变形的动单剪试验研究[D]. 西安: 西安理工大学, 2017. WU Fei-jie. Dynamic Simple Shear Test on Seismic Subsidence Deformation of Unsaturated Loess[D]. Shaanxi: Xi'an University of Technology, 2017. (in Chinese)
[9] HIGHT D W, GENS A, SYMES M J. The development of a new hollow cylinder apparatus for investigating the effects of principal stress rotation in soils[J]. Géotechnique, 1983, 33(4): 355-384. doi: 10.1680/geot.1983.33.4.355
[10] ISHIHARA K, TOWHATA I. Sand response to cyclic rotation of principal stress directions as induced by wave load[J]. Soils and Foundations, 1983, 23(4): 11-26. doi: 10.3208/sandf1972.23.4_11
[11] ISHIHARA K, YAMAZAKI A. Analysis of wave--induced liquefaction in seabed deposits of sand[J]. Soils and Foundations, 1984, 24(3): 85-100. doi: 10.3208/sandf1972.24.3_85
[12] VAID Y P, SAYAO A, et al. Genearlized stres-path dependent Soil behavior with a new hollow cylinder torsional apparatus[J]. Canadian Geotechnical Journal, 1990, 27(5): 601-616. doi: 10.1139/t90-075
[13] SAYAO A, VAID Y P. A critical assessment of stress nonuniformities in hollow cylinder test spacimens[J]. Soils and Foundations, 1991, 31(l): 60-72.
[14] 潘华, 陈国兴. 动态围压下空心圆柱扭剪仪模拟主应力轴旋转应力路径能力分析[J]. 岩土力学, 2011, 32(6): 1701-1712. doi: 10.3969/j.issn.1000-7598.2011.06.018 PAN Hua, CHEN Guo-xing. Analysis of capabilities of HCA to simulate stress paths for principal stressrotation under dynamic confining pressure[J]. Rock and Soil Mechanics, 2011, 32(6): 1701-1712. (in Chinese) doi: 10.3969/j.issn.1000-7598.2011.06.018
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