早龄期混凝土动态力学性能实验研究  

Experimental research on dynamic mechanics of early age concrete

作　　者：李胜林[1] 凌天龙 张会歌 张明悦 Li Shenglin;Ling Tianlong;Zhang Huige;Zhang Mingyue(School of Mechanics and Civil Engineering,China University of Mining&Technology-Beijing,Beijing 100083,China;College of Mechanical and Architectural Engineering,Taishan University,Taian Shandong 271000,China;Yuhong International School,Henan Experimental School,Zhengzhou Henan 450019,China)

机构地区：[1]中国矿业大学(北京)力学与建筑工程学院,北京100083 [2]泰山学院机械与建筑工程学院,山东泰安271000 [3]河南省实验学校裕鸿国际学校,河南郑州450019

出　　处：《矿业科学学报》2020年第5期502-510,共9页Journal of Mining Science and Technology

基　　金：国家自然科学基金(51574247,10272109);教育部高等学校博士学科点专项科研基金(006029009);中央高校基本科研业务专项资金(2010QL05)。

摘　　要：采用75 mm的SHPB实验装置对5种不同龄期的C20和C40混凝土分别进行单次和重复冲击实验,从养护龄期和应变率两方面系统研究了冲击荷载作用下早龄期混凝土的力学性能。单次冲击实验结果表明:相同应变率条件下混凝土的动态抗压强度与龄期呈对数关系,峰值应变随应变率的增加而增大;每一龄期的单轴抗压强度与应变率为幂函数关系,峰值应变则随冲击龄期的增加而减小。重复冲击实验结果表明:龄期小于3 d的混凝土试件受到冲击作用,达到标准养护龄期后其变形能力有所减弱,龄期超过5 d后,早期冲击作用则使其变形能力增强;当首次冲击的应变率超过25 s^-1,达到标准养护龄期后混凝土的动态抗压强度随早期冲击应变率的增加而减小,龄期越大,降低幅度越大。结合C20和C40混凝土实验结果分析认为,混凝土强度等级越低,其力学性能受应变率和冲击龄期的影响越大。The single and double impact experiments were carried out on C20 and C40 concrete at five different ages using a 75 mm SHPB experimental device.The mechanical properties of early age concrete under impact loading were systematically studied from two aspects,namely curing age and strain rate.The results of single impact test show that,on the one hand,the dynamic compressive strength of concrete under the same strain rate is logarithmically related to curing age,while the peak strain of concrete decreases with the increase of impact age.On the other hand,the uniaxial compressive strength at each curing age is in power relationship with the strain rate,and peak strain increases with the increase of strain rate.After the first impact,the concrete specimens are cured to the standard age,and then the second impact test in which the strain rates are the same is carried out to test the mechanical properties of concrete.The results of repeated impact tests show that when the first impact age is less than 3 days,the deformation ability of concrete decreases after reaching the stable age,but increases when impact age is more than 5 days.If the strain rate of the first impact test exceeds 25 s^-1,the dynamic compressive strength will decrease with the increase of the first impact strain rate,and the later the age of the impact,the greater the reduction.Combined with the experimental results of C20 and C40 concrete,it is concluded that the lower the grade of concrete,the more its mechanical property is affected by strain rate and impact age.

关 键 词：混凝土 SHPB实验 养护龄期 应变率 动态力学性能 

分 类 号：TU528[建筑科学—建筑技术科学]