循环荷载下砂土滞回曲线形态特征的定量研究  

Quantitative Evaluation of the Morphological Characteristics of Sand Hysteresis Curve under Cyclic Load

作　　者：宋东松 刘红帅 陈佩云 Song Dongsong;Liu Hongshuai;Chen peiyun(Institute of Geotechnical Engineering,Hebei University,Baoding,Hebei 071002,P.R.China;Hebei Excellent Earthquake Prevention Service Co.,Ltd.,Baoding,Hebei 071027,P.R.China)

机构地区：[1]河北大学岩土工程研究所,河北保定071002 [2]河北极致地震预防服务有限公司,河北保定071027

出　　处：《地下空间与工程学报》2024年第2期449-459,共11页Chinese Journal of Underground Space and Engineering

基　　金：中国地震局工程力学研究所基本科研业务费专项(2019EEEVL0202);河北省高等学校科学技术研究项目(ZD2020157);河北省自然科学基金(E2020201017)。

摘　　要：以福建标准砂(粒径0.5~1.0 mm)为试验对象进行动三轴试验,研究了围压、相对密度、振次对砂土滞回曲线的影响。分别采用滞回曲线长轴斜率K、滞回曲线的面积S、滞回曲线压拉半轴面积差S′、不闭合程度σ_(P)以及短长轴比α对福建标准砂滞回曲线形态特征进行定量描述。结果表明:K随着应变增大而减小;当应变较小(<0.1%)时,随振次的增大K值逐渐增大,但当应变较大(>0.1%)时,K值随振次的增大而减小;围压对K值的影响比较明显,K值随着围压的增大而增大,而相对密度影响则较小;在应变(<0.1%)发展前期,围压和相对密度等对砂土的滞回曲线S、S′、σ_(P)基本无影响,而随应变的增大,S、S′、σ_(P)逐渐增大,但它们都随振次的增大在逐渐减小;α随着应变的增加先减小后呈指数增大,其应变转折点随围压的增大在逐渐后移,α随着围压的增大而减小,但随着振次的增大而增大,相对密度对α的影响规律不明。Taking Fujian Standard Sand(particle size 0.5 mm~1.0 mm)as the test object,dynamic triaxial test was carried out to study the influence of confining pressure,relative density and vibration frequency on the hysteresis curve of sand.The long axis slope of hysteretic curve K,the area of the hysteretic curve S,the area difference between the positive and negative partial stresses of the hysteretic curve S′,the degree of non-closureσp and the dissipation modulusαof hysteretic curve are used to quantify the morphological characteristics of the hysteresis curve of Fujian standard sand.The results show that the value of K decreases with the increase of cyclic strain and the decrease of the effective confining pressure.When the strain is small(<0.1%),K gradually increases with the increase of the cycle times whereas an opposite trend is observed for strain greater than 0.1%.Relative density slightly affects the values of K.In the small strain range(<0.1%),the values of S,S′andσp are not sensitive to the effective confining pressure and the relative density.While with the increase of strain,S and S′values increase exponentially but decrease as the cycle times increases.The value ofαdecreases first and then increases exponentially with the increase of strain,and the strain turning point moves backward with the increase of the effective confining pressure.Lower values ofαare observed for larger confining pressure and the smaller cycle times.However,the effect of the relative density onαis unclear.

关 键 词：砂土 滞回曲线 形态特征 损耗模量 刚度 

分 类 号：TU41[建筑科学—岩土工程]