黄土的动变形特性及模型研究  

Dynamic Deformation Characteristics and Modeling of Loess

作　　者：石娇 张希栋 SHI Jiao;ZHANG Xi-dong(College of Urban and Rural Construction,Shanxi Agricultural University,Jinzhong 030801,China;School of Civil and Environmental Engineering,University of New South Wales,Sydney 2052,Australia)

机构地区：[1]山西农业大学城乡建设学院,山西晋中030801 [2]新南威尔士大学土木与环境工程学院

出　　处：《长江科学院院报》2018年第9期114-120,共7页Journal of Changjiang River Scientific Research Institute

基　　金：国家自然科学基金项目(51178392);161青年科技创新项目(J141602002)

摘　　要：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。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 

分 类 号：TU444[建筑科学—岩土工程]