超重力模型试验干-饱和砂动剪切模量阻尼比特性研究  

Study on the characteristics of shear modulus and damping ratio between dry sand and saturated sand in centrifuge model test

作　　者：王体强 王永志[1,2] 梁小丛 王德咏[3] 陈卓识[1,2] WANG Tiqiang;WANG Yongzhi;LIANG Xiaocong;WANG Deyong;CHEN Zhuoshi(Key Laboratory of Earthquake Engineering and Engineering Vibration,Institute of Engineering Mechanics,China Earthquake Administration,Harbin,Heilongjiang 150080,China;Key Laboratory of Earthquake Disaster Mitigation,Ministry of Emergency Management,Harbin,Heilongjiang 150080,China;CCCC Fourth Harbor Engineering Institute Co.,Ltd.,Guangzhou,Guangdong 510230,China)

机构地区：[1]中国地震局工程力学研究所地震工程与工程振动重点实验室,黑龙江哈尔滨150080 [2]地震灾害防治应急管理部重点实验室,黑龙江哈尔滨150080 [3]中交四航工程研究院有限公司,广东广州510230

出　　处：《岩石力学与工程学报》2023年第6期1546-1559,共14页Chinese Journal of Rock Mechanics 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资助项目(2019EEEVL0203);国家自然科学基金资助项目(51609218);黑龙江省自然科学基金资助项目(YQ2019E035)。

摘　　要：动剪切模量阻尼比是土动力学与岩土地震工程的重要动力学指标,其认识和本构关系多基于室内单元试验建立。相对于室内单元试验,超重力模型试验具有更真实的应力边界、加载方式和排水条件,但在动模量阻尼比领域鲜见研究。基于超重力模型对比试验,揭示了干砂、饱和砂剪应力-剪应变滞回圈的形式差异,对比了动模量和阻尼比随埋深、剪应变、振动序次等变化特征与规律。结果表明:干砂滞回圈呈椭圆形,饱和砂滞回圈呈不规则、不光滑的哑铃形,液化后饱和砂剪应变迅速增大,0.2 g荷载条件下干砂、饱和砂最大剪应变分别为0.3%和1%。干砂、饱和砂的动剪切模量均较好的符合Hardin双曲线模型:即其随剪应变增加而降低、随埋深增加而增大、随振动次数增加引起土体振密而增大。最大动剪切模量及随深度、振动序次的变化基本一致,受饱和与否影响较小。干砂、饱和砂的参考应变分别为0.1%~0.35%和0.05%~0.18%,不同深度、荷载下前者均为后者约2倍,并随埋深、密实度的增加而呈增大趋势。干砂阻尼比随剪应变、埋深变化具有良好规律,离散性小,而饱和砂阻尼比规律不明显,离散性大,与液化后土体强度失效引起的传感器位置变化、测试准确性和分析方法可靠性相关。研究结果,为认识超重力模型试验动模量阻尼比响应特征及对比单元试验动模量阻尼比可靠性,提供技术支撑和指导依据。Dynamic shear modulus and damping ratio are significant dynamic indicators of soil dynamics and geotechnical earthquake engineering,and their constitutive relationships are mostly established and recognized based on unit tests.Compared with the unit tests,the centrifuge model tests have more realistic stress boundaries,loading schemes and drainage conditions,but there are rarely studies on dynamic modulus and damping ratio.The form differences of the shear stress-strain hysteresis loop of dry sand and saturated sand are revealed,and the characteristics and laws of dynamic modulus and damping ratio with burial depth,shear strain and vibration order are compared based on the centrifuge model comparison tests.The results show that the hysteresis cycle of dry sand is oval,but the hysteresis cycle of saturated sand is irregular and non-smooth dumbbell shape.The shear strain of saturated sand increases rapidly after liquefaction,and the maximum shear strains of dry sand and saturated sand under 0.2 g load are 0.3%and 1%,respectively.The dynamic shear moduli of dry sand and saturated sand obey the Hardin hyperbola model well,which decrease with the increase of shear strain,increase with the increase of burial depth,and increase with the increase of vibration times,which causes the soil vibration density.The maximum dynamic shear modulus and their changes with depth and vibration order are basically the same,and are less affected by saturation.The reference strains of dry sand and saturated sand are 0.1%-0.35%and 0.05%-0.18%,respectively,and the reference strains of dry sand under different depths and loads are about twice that of the saturated sand,and they increase with the increase of burial depth and density.The damping ratio of dry sand has a good law with the variation of shear strain and burial depth,and the discreteness is small.However,the damping ratio of saturated sand is not obvious,and the discreteness is large,which is related to the change of sensor position,the test accuracy and the reliability of the ana

关 键 词：土力学 动力离心试验 剪切模量 阻尼比 反演分析 

分 类 号：TU43[建筑科学—岩土工程]