利用SDT-20型双向动三轴仪对原状黄土和重塑黄土的动变形特性进行研究,定性分析了不同试验参数对原状和重塑黄土动剪切模量和动剪切应变累积特性的影响。基于小应变前提,忽略试样在加载过程中的径向应变,并利用其轴向动应变推算出试样在动力加载过程中的孔隙比变化,作出e-σd曲线并分析了黄土试样的动力压缩特性。分析发现,和静力压缩不同,黄土的结构性在动力压缩过程中并没有表现出来,原状黄土和重塑黄土在动荷载作用下经历相似的形变过程,其e-σd曲线均存在明显的拐点,原状和重塑黄土均存在临界动应力σdc。当σd<σdc时,黄土的动变形发展缓慢;而当σd>σdc时,黄土的动变形急剧增大并迅速发生破坏。此外,提出双曲模型对黄土在循环荷载作用下的动应变累积特性进行了描述,并利用差分进化法求得模型参数,发现双曲模型可以较好地描述黄土在动荷载作用下的应变累积特性。
Abstract
With SDT-20 dynamic triaxial apparatus, the dynamic deformation properties of both intact and remolded loess are explored. The effects of different test parameters on the dynamic shear modulus and the accumulation of dynamic shear strain are qualitatively analyzed. In the prerequisite of small strain and taking no account of radial strain during loading, the void ratio of sample is derived according to axial dynamic strain, and the dynamic compression behavior of loess samples is analyzed with e-σd curves. Different from those under static loading, the characteristics of compression of loess are not revealed under dynamic loading, and the structure of intact loess is not obviously reflected as both intact and remolded loess experience a similar deformation process under dynamic loading. A turning point exists in e-σd curve of intact loess as well as that of remolded loess, which implies a critical dynamic stress for both intact and remolded loess. When dynamic stress is less than critical dynamic stress, the dynamic deformation of loess develops slowly; but when dynamic stress is greater than critical stress, the dynamic deformation increases dramatically and loess samples are destroyed quickly. In addition, a hyperbolic model is established to modeling the accumulation characteristics of dynamic strain of loess, and the model parameters are calculated with differential evolution method. By comparing the estimation of hyperbolic model with experimental data, we conclude that the proposed hyperbolic model could well describe the deformation properties of loess under dynamic loading.
关键词
黄土 /
动剪切模量 /
动剪应变 /
动力压缩 /
动剪应变累积模型
Key words
loess /
dynamic shear modulus /
dynamic shear strain /
dynamic compression /
model for dynamic strain accumulation
{{custom_sec.title}}
{{custom_sec.title}}
{{custom_sec.content}}
参考文献
[1] 王 强,孙军杰,王兰民.黄土震陷及相关问题探讨[J]. 中国地震,2012,28(4):351-359.
[2] GB50011—2010,建筑抗震设计规范[S].北京:中国建筑工业出版社,2010.
[3] 李昭淑,崔 鹏.1956年华县大地震的次生灾害[J].山地学报,2007,25(4):425-430.
[4] 邓龙胜,范 文.宁夏海原8.5级地震诱发黄土滑坡的变形破坏特征及发育机理[J].灾害学,2013,28(3):30-37.
[5] ZHANG D X, WANG G H. Study of the 1920 Haiyuan Earthquake-induced Landslides in Loess(China)[J]. Engineering Geology, 2007, 94(1/2): 76-88.
[6] ZHANG Z Z, ZHANG D L, LIU H M. Comprehensive Study on Seismic Subsidence of Loess under Earthquake[J]. Northwest Seismological Journal,2005,27(1): 36-41,46.
[7] DELFOSSE-RIBAY E, DJERAN-MAIGRE I, CABRILLAC R, et al. Shear Modulus and Damping Ratio Grouted Sand[J]. Soil Dynamics and Earthquake Engineering,2004,24(6):461-471.
[8] WANG G X, KUWANO J. Modeling of Strain Dependency of Shear Modulus and Damping of Clayey Sand[J]. Soil Dynamics and Earthquake Engineering,1999,18(6):463-471.
[9] 骆亚生,田堪良.非饱和黄土的动剪模量与阻尼比[J].水利学报,2005,36(7):830-834.
[10]陈存礼,杨 鹏,何军芳.饱和击实黄土的动力特性研究[J].岩土力学,2007,28(8):1551-1556.
[11]王志杰.复杂初始应力状态下黄土动剪切模量与阻尼比特性试验研究[D]. 杨凌:西北农林科技大学, 2010.
[12]刘建民,周云东,张立志,等.饱和重塑黄土液化应变发展试验研究[J].江西理工大学学报,2012,33(1):39-43.
[13]孙海妹,王兰民,王 平,等.振动荷载作用下黄土应变增长特征试验研究[J].地下空间与工程学报,2011,7(6):1103-1107.
[14]邓 津,王兰民,吴志坚.弹塑性黄土微结构与动变形模型的建立与分析[J].岩石力学与工程学报,2013,32(增2):3995-4001.
[15]谷天峰,王家鼎,任 权,等.循环荷载作用下黄土边坡变形研究[J].岩石力学与工程学报,2009,28(增1):3156-3162.
[16]谢定义.土动力学[M].北京:高等教育出版社,1988:5,46,51,142,177.
[17]刘文化,杨 庆,唐小微,等.干湿循环条件下粉质黏土在循环荷载作用下的动力特性试验研究[J].水利学报,2015,46(4):425-432.
[18]张希栋,骆亚生.双向动荷载下黄土的动剪切模量特性研究[J].岩土力学,2015,36(9):2591-2598.
[19]MONISMITH C L, OGAWA N, FREEME C R. Permanent Deformation Characteristics of Subgrade Soils due to Repeated Loading[J]. Transportation Research Record, 1975,537:1-17.
[20]臧 濛,孔令伟,曹 勇.描述循环荷载作用下黏土累积变形的改进模型[J].岩土力学,2017,38(2):435-442.
基金
国家自然科学基金项目(51178392);161青年科技创新项目(J141602002)
PDF(4641 KB)
