冲击荷载作用下黄土动力特性研究  

Dynamic Mechanical Behavior of Loess Under Impact Loading

作　　者：童朝霞[1] 邢大鹏 郝志宾 许国一 冯锦艳[1] TONG Zhao-xia;XING Da-peng;HAO Zhi-bin;XU Guo-yi;FENG Jin-yan(School of Transportation Science and Engineering,Beihang University,Beijing 100191,China)

机构地区：[1]北京航空航天大学交通科学与工程学院,北京100191

出　　处：《中国公路学报》2025年第1期73-82,共10页China Journal of Highway and Transport

基　　金：国家重点研发计划项目(2023YFB2603605)。

摘　　要：为了研究黄土在冲击荷载作用下的动力响应特性,利用可靠的分离式霍普金森压杆(SHPB)试验技术,对含水率分别为13%、16%、19%和22%的黄土试样进行了多组不同应变率的冲击压缩试验,撞击杆的设计速度分别为4、6、8、10 m·s^(-1)。试验结果表明:冲击荷载作用下黄土试样的动应力-应变响应过程具有明显的分段性,可划分为弹性变形、塑性流动和破坏3个阶段;应变率和含水率的变化对黄土试样的动力特性影响显著,其中应变率的增加导致黄土试样出现塑性流动阶段延长的现象,含水率的增加则使得黄土试样的动应力-应变发展过程表现出由以塑性流动为主向以脆性破坏为主的转化趋势;黄土试样的屈服强度、破坏强度和破坏应变均随着应变率的增加而增加,随着含水率的增加而减小;黄土试样的压缩波速主要受含水率的影响,含水率越高,波速越大。采用考虑损伤演化的Z-W-T元件组合模型对由试验获得的黄土试样动力响应进行了模拟,结果显示由元件组合模型模拟得到的黄土试样动应力-动应变关系曲线与由分离式霍普金森压杆试验得到的动应力-应变曲线具有很好的一致性;在此基础上,对元件组合模型参数进行了深入分析,发现黄土试样对高应变率的响应比对低应变率的响应更为敏感。To investigate the dynamic response characteristics of loess under impact loading,a series of impact compression tests with varied strain rate were conducted on loess samples with four different moisture contents of 13%,16%,19%,and 22%using the split Hopkinson pressure bar(SHPB)testing technique.The design speeds of the impact rod were 4,6,8,and 10 m·s^(-1).The experimental results show that the dynamic stress-strain relationship of loess under impact loading exhibits obvious subsection characteristics.It can be divided into three stages:elastic deformation,plastic flow,and failure.The strain rate and moisture content significantly influence the dynamic characteristics of the loess samples.An increase in strain rate prolongs the plastic flow process of the loess,while an increase in moisture content leads to a transition from a predominantly plastic flow characteristic to a brittle failure in the dynamic stress-strain development of the loess.The yield strength,failure strength,and failure strain of the loess increase with the increase in the strain rate and decrease with the increase in the moisture content.The compressive wave velocities of the loess samples are primarily influenced by the moisture content.The higher moisture content results in higher compressive wave velocities.Additionally,a Z-W-T component model considering damage evolution was used to simulate the dynamic response of the loess.The simulated stress-strain relationship of the loess shows a good agreement with the SHPB experimental results.Further analysis of the model parameters reveals that the response of the loess is considerably more sensitive to high strain rates than to low strain rates.

关 键 词：路基工程 动力特性 分离式霍普金森压杆 黄土 含水率 元件组合模型 高应变率 

分 类 号：U416.1[交通运输工程—道路与铁道工程]