冻土冲击动态应力-应变曲线特征及汇聚现象分析  

CHARACTERISTICS OF STRESS-STRAIN CURVES AND CONVERGENCE PHENOMENON OF FROZEN SOIL UNDER DYNAMIC LOADING

作　　者：马悦[1] 朱志武[1,2,3] 马巍 宁建国[3] 

机构地区：[1]西南交通大学力学与工程学院,四川成都610031 [2]中科院寒早所冻土工程国家重点实验室,甘肃兰州730000 [3]北京理工大学爆炸科学与技术国家重点实验室,北京100081

出　　处：《工程力学》2015年第10期52-59,共8页Engineering Mechanics

基　　金：国家自然科学基金项目(11172251);冻土工程国家重点实验室开放基金项目(SKLFSE201001);爆炸科学与技术国家重点实验室(北京理工大学)开放课题项目(KFJJ13-10M);四川省青年科技创新团队项目(2013TD0004)

摘　　要：研究通过系统的霍普金森压杆实验,分析了冻土冲击动态应力-应变曲线的特征,验证了冻土的应变汇聚现象,揭示了产生这一现象的原因。研究发现应变率、实验冻结温度和初始含水量等参数对应力-应变曲线均有影响,而应变汇聚现象产生的首要条件是具有相同的加载应变率,与温度和初始含水量等参数无关。同时,冻土的动态裂纹损伤类型和裂纹损伤演化方式能够直接影响汇聚现象中应力-应变曲线的形状,温度损伤现象是冻土特有的动态力学性能和应变汇聚现象产生的重要原因。此外,霍普金森压杆实验特殊的冲击动态加载方式和实验基本假设产生了特定的加载历程,实验加载条件决定了应变汇聚现象的汇聚点位置。因此,应变汇聚现象反映了冲击动态加载条件下冻土特有的力学性能,是冻土固有性质和实验手段共同作用的结果。Based on the systemic impact loading experiments of frozen soil, this research analyzes the characteristics of the dynamic stress-strain curves and the necessity of such phenomenon in split Hopkinson pressure bar experiments. And a convergence phenomenon of strain is concluded from the experiment results. It shows that parameters such as strain rate, freezing temperature and initial moisture content have effects on the dynamic stress-strain curve. The occurrence prerequisite of strain convergence phenomenon is an identical strain rate but not on the freezing temperature and initial moisture content. The research suggests that thermal damage and crack damage take an important role in the dynamic stress-strain curve and in the strain convergence phenomenon of frozen soil. Crack damage is one common form in each material, which contributes to the shape of stress-strain curve immediately. Thermal damage describes the effects of transient temperature rising, whichleads to metabolic ice ratio and is an important element for the dynamic properties of frozen soil. Moreover, the loading process of split Hopkinson pressure bar experiment is another important factor of strain convergence phenomenon, which determines the convergence position. Generally speaking, the convergence phenomenon is a peculiar trial characteristic of frozen soil in split Hopkinson pressure bar experiment that reflects unique dynamic mechanical properties.

关 键 词：冻土 本构关系 霍普金森压杆 冲击实验 汇聚现象 

分 类 号：O347.3[理学—固体力学]