Dynamic shear modulus and damping ratio of saturated loess
WANG Qian1，2，MA Jinlian1，2，MA Haiping2，WANG Jun1，2，WANG Lanmin1，2，GAO Zhongnan2，ZHONG Xiumei1，2
(1. Key Laboratory of Loess Earthquake Engineering，China Earthquake Administration and Gansu Province，Lanzhou，Gansu 730000，China；2. Lanzhou Institute of Seismology，China Earthquake Administration，Lanzhou，Gansu 730000，China)
Abstract：In order to investigate the dynamic behaviors and influence factors of saturated loess，a series of dynamic triaxial tests were conducted to analyze the dynamic shear modulus and damping ratio of the loess sampled from 11 different sites in Loess Plateau，and the dynamic shear modulus ratio and the damping ratio were obtained by fitting the test results. The regional differences of the dynamic shear modulus ratio and damping ratio of saturated loess were discussed，and the differences of the dynamic shear modulus ratio and the damping ratio between the saturated loess and the original loess were also analyzed. In addition，influence of physical indexes on fitting parameters of the dynamic modulus and the damping ratio of the saturated loess was analyzed. The results indicate that the dynamic constitutive relation of the saturated loess obeys the Hardin-Drnevich model. The regional distributive characteristics of the loess have a significant influence on the damping ratio while slight on the dynamic shear modulus ratio. Both the value and the regional discreteness of the dynamic shear modulus ratio of the saturated loess are much smaller than those of the original loess. In the same site，however，the damping ratio of the saturated loess is markedly larger than that of the original loess，which is influenced by the loess structure. The maximum dynamic shear modulus of the saturated loess is greatly influenced by the initial void ratio，and the changes of the ultimate dynamic shear stress amplitude and the maximum damping ratio are mainly caused by the variation of structural characteristics of the loess resulted from the increase of the clay content.
[1] 王兰民，石玉成，刘 旭，等. 黄土动力学[M]. 北京：地震出版社，2003：85–143.(WANG Lanmin，SHI Yucheng，LIU Xu，et al. Loess dynamics[M]. Beijing：Seismological Press，2003：85–143.(in Chinese))
[2] 王永焱，林在贯. 中国黄土的结构特征及物理力学性质[M]. 北京： 科学出版社，1990：105–172.(WANG Yongyan，LIN Zaiguan. The China loess structure features and its physical and mechanical properties[M]. Beijing：Science Press，1990：105–172.(in Chinese))
[3] 中华人民共和国国家标准编写组. GB18036—2015 中国地震动参数区划图[S]. 北京：中国标准出版社，2015.(The National Standards Compilation Group of the People′s Republic of China. GB18036—2015 Seismic ground motion parameters zonation map of China[S]. Beijing：Standards Press of China，2015.(in Chinese))
[4] ISHIHARA K，OKUSA S，OYAGI N，et al. Liquefaction-induced flow slide in the collapsible loess deposit in soviet Tajik[J]. Soils and Foundations，1990，30(4)：73–89.
[5] 王兰民，刘红玫，李 兰，等. 饱和黄土液化机理与特性的试验研究[J]. 岩土工程学报，2000，22(1)：89–94.(WANG Lanmin，LIU Hongmei，LI Lan，et al. Laboratory study on the mechanism and behaviors of saturated loess liquefaction[J]. Chinese Journal of Geotechnical Engineering，2000，22(1)：89–94.(in Chinese))
[6] WANG S Y，LUNA R. Compressibility characteristics of low-plasticity silt before and after liquefaction[J]. Journal of Materials in Civil Engineering，2014，26(6)：040140141–1–6.
[7] 邓龙胜，范 文，贺龙鹏. 随机地震荷载作用下黄土的液化特性[J].岩石力学与工程学报，2012，31(6)：1 274–1 280.(DENG Longsheng，FAN Wen，HE Longpeng. Liquefaction property of seismic loess under stochastic load[J]. Chinese Journal of Rock Mechanics and Engineering，2012，31(6)：1 274–1 280.(in Chinese))
[8] HARDIN B O，DRNEVICH V P. Shear modulus and damping in soils：Design equations and curves[J]. Journal of the Soil Mechanics and Foundations Division，ASCE，1972，98(7)：667–692.
[9] SEED H B，IDRISS I M. Soil moduli and damping factors for dynamic response analyses[R]. Berkely，Calif.：[s. n.]，1970.
[10] MARTIN P P，SEED H B. One-dimensional dynamic ground response analyses[J]. Journal of the Geotechnical Engineering Division，ASCE，1982，108(7)：935–952.
[11] 袁晓铭，孙 锐，孙 静，等. 常规土类动剪切模量比和阻尼比试验研究[J]. 地震工程与工程振动，2000，20(4)：133–139.(YUAN Xiaoming，SUN Rui，SUN Jing，et al. Laboratory experimental study on dynamic shear modulus ratio and damping ratio of soils[J]. Earthquake Engineering and Engineering Vibration，2000，20(4)：133–139.(in Chinese))
[12] 陈国兴，刘雪珠. 南京及其邻近地区新近沉积土的动剪切模量和阻尼比试验研究[J]. 岩石力学与工程学报，2004，23(8)：1 403–1 410. (CHEN Guoxing，LIU Xuezhu. Testing study on ratio of dynamic shear modulus and ratio of damping for recently deposited soils in Nanjing and its neighboring areas[J]. Chinese Journal of Rock Mechanics and Engineering，2004，23(8)：1 403–1 410.(in Chinese)).
[13] 尚守平，刘方成，杜运兴，等. 应变累积对黏土动剪切模量和阻尼比影响的试验研究[J]. 岩土力学，2006，27(5)：683–688.(SHANG Shouping，LIU Fangcheng，DU Yunxing，et al. Experimental study on clay strain accumulation effects on dynamic shear modulus and damping ratio[J]. Rock and Soil Mechanics，2006，27(5)：683–688. (in Chinese))
[14] 贾鹏飞，孔令伟，王 勇，等. 低幅值小应变振动下土体弹性刚度的非线性特征与表述方法[J]. 岩土力学，2013，34(11)：3 145–3 151. (JIA Pengfei，KONG Lingwei，WANG Yong，et al. Nonlinear characteristics and determinate method of elastic stiffness for soils due to low-amplitude small-strain vibrations[J]. Rock and Soil Mechanics，2013，34(11)：3 145–3 151.(in Chinese))
[15] 李启鹞，程显尧，蔡东艳. 地震荷载下的黄土动力特性[J]. 西安冶金建筑学院学报，1985，(3)：9–37.(LI Qiyao，CHENG Xianyao，CAI Dongyan. Dynamic characteristics of loess under seismic load[J]. Journal of Xi?an Institute of Metallurgy and Construction Engineering，198，(3)：9–37.(in Chinese)).
[16] 朱克廉，周新赞，蔡东艳. 黄土动模量和阻尼比的试验研究[J]. 西安建筑科技大学学报：自然科学版，1992，24(2)：1 288–1 296. (ZHU Kelian，ZHOU Xinzan，CAI Dongyan. Experimental study on the dynamic modulus and damping ratio of loess[J]. Journal of Xi?an University of Architecture and Technology：Natural Science，1992，24(2)：1 288–1 296.(in Chinese))
[17] 王志杰，骆亚生，王瑞瑞，等. 不同地区原状黄土动剪切模量与阻尼比试验研究[J]. 岩土工程学报，2010，32(9)：1 464–1 469. (WANG Zhijie，LUO Yasheng，WANG Ruirui，et al. Experimental study on dynamic shear modulus and damping ratio of undisturbed loess in different regions[J]. Chinese Journal of Geotechnical Engineering，2010，32(9)：1 464–1 469.(in Chinese))
[18] 胡仲有，骆亚生，李 焱，等. 不同地区黄土阻尼比变化特性试验研究[J]. 地震工程与工程振动，2010，30(2)：167–172.(HU Zhongyou，LUO Yasheng，LI Yan，et al. Experimental study on damping ratio variation characteristics of loess in different areas[J]. Earthquake Engineering and Engineering Vibration，2010，30(2)：167–172.(in Chinese))
[19] 胡志平，王 强，张雨禾，等. 应力、应变控制下压实黄土动力特性研究[J]. 地震工程学报，2018，40(6)：1 161–1 167.(HU Zhiping，WANG Qiang，ZHANG Yuhe，et al. Dynamic Characteristics of Compacted Loess under Controlled-stress and Controlled-strain Modes[J]. China Earthquake Engineering Journal，2018，40(6)：1 161–1 167.(in Chinese))
[20] 慕焕东，孙 萍，李荣建，等. 磐安结构性黄土动阻尼特征及其演化规律研究[J]. 地质力学学报，2017，23(6)：935–942.(MU Huandong，SUN Ping，LI Rongjian，et al. Dynamic damping characteristics and evolution law of Pan?an structural loess[J]. Journal of Geomechanics，2017，23(6)：935–942.(in Chinese))
[21] 邵生俊，罗爱忠，于清高，等. 加荷增湿作用下Q3黏黄土的结构损伤特性[J]. 岩土工程学报，2006，28(12)：2 077–2 081.(SHAO Shengjun，LUO Aizhong，YU Qinggao，et al. Structural damage properties of Q3 loess under triaxial loading and moistening[J]. Chinese Journal of Geotechnical Engineering，2006，28(12)：2 077– 2 081.(in Chinese))
[22] 罗爱忠，邵生俊. 湿载耦合作用下黄土结构性损伤演化及本构关系[J]. 岩石力学与工程学报，2012，31(4)：841–847.(LUO Aizhong，SHAO Shengjun. Structural damage evolution and constitutive relation of loess under coupling of stress and moisture[J]. Chinese Journal of Rock Mechanics and Engineering，2012，31(4)：841–847.(in Chinese))
[23] 中华人民共和国行业标准编写组. SL237–032—1999 土工试验规程[S]. 北京：中国水利水电出版社，1999.(The Professional Standards Compilation Group of the People′s Republic of China. SL237–032—1999 Specification of soil test[S]. Beijing：China Water Power Press，1999.(in Chinese))
[24] 谢定义. 土动力学[M]. 西安：西安交通大学出版社，1988：238–240.(XIE Dingyi. Soil dynamics[M]. Xi?an：Xi?an Jiaotong University Press，1988：238–240.(in Chinese))
[25] RONG M，WANG Z，WOOLERY E，et al. Nonlinear site response from the strong ground-motion recordings in western China[J]. Soil Dynamics and Earthquake Engineering，2016，82：99–110.
[26] SHEANDER N，RAJ S，JOHN A. Characteristics of nonlinear response of deep saturated soil deposits[J]. Bulletin of the Seismological Society of America，1997，87(2)：342–355.
[27] 中华人民共和国国家标准编写组. GB50025—2004 湿陷性黄土地区建筑设计规范[S]. 北京：中国建筑工业出版社，2004.( The National Standards Compilation Group of the People′s Republic of China. GB50025—2004 Code for building construction incollapsible loess regions[S]. Beijing：China Architecture and Building Press，2004.(in Chinese))
[28] 高国瑞. 黄土的显微结构分类与湿陷性[J]. 中国科学，1980，10(12)：1 203–1 208.(GAO Guorui. Classification of micro structure and collapsibility of the loess[J]. Scientia Sinica，1980，10(12)：1 203–1 208.(in Chinese))
[29] 雷祥义. 中国黄土的孔隙类型与湿陷性[J]. 中国科学(B辑)，1987，17(12)：1 309–1 316.(LEI Xiangyi. Pore types of Chinese loess and its collapsibility[J]. Science in China(Ser. B)，1987，17(12)：1 309–1 316. (in Chinese))
2019, Vol. 38 
