循环荷载下渭北地区黄土动力特性分析  

Analysis of dynamic properties of loess in Weibei area under cyclic loading

作　　者：张勇[1,2] 钱家志 ZHANG Yong;QIAN Jiazhi(School of Civil Engineering,Xi′an Univ.of Arch.&Tech.,Xi′an 710055,China;School of Management,Xi′an Univ.of Arch.&Tech.,Xi′an 710055,China)

机构地区：[1]西安建筑科技大学土木工程学院,陕西西安710055 [2]西安建筑科技大学管理学院,陕西西安710055

出　　处：《西安建筑科技大学学报（自然科学版）》2024年第4期535-543,共9页Journal of Xi'an University of Architecture & Technology(Natural Science Edition)

基　　金：引汉济渭联合基金项目(2021JLM-52)。

摘　　要：为研究渭北地区的黄土动力学特性分析,通过TYS-20型土动三轴试验机,研究不同围压下黄土的动本构关系以及动骨干曲线,分析黄土的动剪模量比和阻尼比的关系,提出动剪切模量衰减模型和阻尼增长模型;研究不同围压对黄土动强度和残余应变的影响,从理论上解释黄土动力特性变化的原因,从而更好地保证黄土震陷对地下空间影响最小化;最后对比黄土震前震后微结构,并进行机理分析对该地区地下空间发展提供理论意义.研究结果显示:黄土的动本构关系符合双曲线模型;动剪模量比随动剪应变呈负指数衰减关系,而阻尼比随动剪应变呈对数关系增长;动强度和动强度指标受试验条件的影响较大,其中动强度随围压的增大而增大,表明动强度分析能较好地说明黄土的动力特性变化规律;根据电子显微镜对比土体震前震后微结构,并进行机理分析,为该地区地下空间发展提供理论支持.通过研究表明,渭北地区黄土在循环荷载作用下不易产生振动变形,属于轻微震陷区.In order to study the dynamic characteristics of loess in Weibei area,the dynamic constitutive relationship and dynamic backbone curve of loess under different confining pressures were studied by TYS-20 soil dynamic triaxial testing machine.The relationship between dynamic shear modulus ratio and damping ratio of loess was analyzed,and a dynamic shear modulus attenuation model and a damping growth model were proposed.The influence of different confining pressures on the dynamic strength and residual strain of loess was studied,and the reasons for the change of dynamic characteristics of loess were explained theoretically,so as to better ensure the minimization of the influence of loess seismic subsidence on underground space.Finally,the microstructure of loess before and after earthquake was compared,and the mechanism analysis was carried out to provide theoretical significance for the development of underground space in this area.The results show that the dynamic constitutive relationship of loess conforms to the hyperbolic model,and the dynamic shear modulus ratio decreases exponentially with the dynamic shear strain,while the damping ratio increases logarithmically with the dynamic shear strain.The dynamic strength and dynamic strength index are greatly affected by the test conditions,and the dynamic strength increases with the increase of confining pressure,indicating that the dynamic strength analysis can better explain the dynamic characteristics of loess.The microstructure of soil before and after earthquake is compared by electron microscope.The microstructure of soil before and after earthquake is compared by electron microscope,and the mechanism analysis is carried out,which provides theoretical support for the development of underground space in this area.The results show that the loess in Weibei area,which belongs to slight seismic subsidence area,is less prone to vibration deformation under cyclic loading.

关 键 词：动本构关系 动剪切模量比 阻尼比 动强度 黄土震陷 

分 类 号：TU444[建筑科学—岩土工程]