摘要
为了研究硫酸盐冻融环境下沙漠砂混凝土(DSC)冻融损伤和声发射(acoustic emission,AE)特性,开展不同Na2SO4溶液质量分数(3%、5%、7%)、冻融循环次数(0、25、50、75、100、125次)沙漠砂混凝土(沙漠砂替代率DSRR,0、20%、40%)冻融后单轴受压试验,利用声发射技术对试验全过程进行动态监测,分析Na2SO4溶液质量分数、冻融循环次数和DSRR对沙漠砂混凝土抗冻性能的影响,建立硫酸盐冻融环境下沙漠砂混凝土声发射累计振铃计数与宏观力学特性内在联系。结果表明:峰值应力、声发射振铃计数峰值和Ib峰值均随冻融循环次数增加呈降低趋势,随DSRR增加逐渐增大,DSRR为40%沙漠砂混凝土整体力学性能和抗冻性能较好,质量分数7%Na2SO4溶液沙漠砂混凝土冻融破坏程度大于3%、5%Na2SO4溶液。声发射相对累计振铃计数与相对峰值应力满足指数函数关系,相关系数R2>0.90。硫酸盐冻融后沙漠砂混凝土试件在单轴受压过程中拉伸型和剪切型裂纹交替转化,拉伸型裂纹占主导地位,剪切型裂纹起促进作用。Ib值曲线的震荡变化特征与沙漠砂混凝土非均匀性以及微裂纹和宏观裂缝发展情况密切相关,反映了沙漠砂混凝土内部损伤演化过程。研究成果可为沙漠砂混凝土在硫酸盐冻融环境下工程实际应用提供参考。
In order to study the freeze-thaw damage and acoustic emission(AE)characteristics of desert sand concrete(DSC)under sulfate freeze-thaw environments,uniaxial compression tests were conducted to analyze the effects of the mass fractions of Na2SO4 solution(3%,5%,7%),the number of freeze-thaw cycles(0,25,50,75,100,and 125)and desert sand replacement ratio(DSRR,0,20%,40%)on the freeze-thaw performance of DSC.The AE technology was used to monitor the whole process of DSC under uniaxial compression.The relation between the cumulative ring count of DSC under sulfate freeze-thaw environment and its macroscopic mechanical properties was established.The results show that the peak stress,the peak of AE ring counts,and Ib-value show gradually decreasing trends with increasing number of freeze-thaw cycles and gradually increasing trends with increasing DSRR,respectively.The DSC with DSRR of 40%has better mechanical properties and frost resistance.The freeze-thaw damage of the DSC subjected to Na2SO4 solution with the mass fractions of 7%is greater than those of 3%and 5%.The relative cumulative ring count of AE and the relative peak stress follow the exponential function relationship,with a correlation coefficient R2>0.90.At the course of uniaxial compression of the DSC after sulfate freeze-thaw cycles,alternative transformations of tensile and shear cracks were produced,with tensile cracks being dominant and shear cracks playing a promoting role.The oscillatory variation characteristics of the Ib-value curves are closely related to the non-uniformity of the DSC as well as the development of microcracks and macroscopic cracks,which reflects the evolution of the internal damage of the DSC.The research results can provide a reference for the engineering applications of the DSC in freeze-thaw environments.
作者
刘浩天
孙竟鹏
刘海峰
董水博
车佳玲
杨维武
LIU Haotian;SUN Jingpeng;LIU Haifeng;DONG Shuibo;CHE Jialing;YANG Weiwu(School of Civil and Hydraulic Engineering,Ningxia University,Yinchuan 750021,China)
出处
《铁道科学与工程学报》
北大核心
2025年第4期1647-1661,共15页
Journal of Railway Science and Engineering
基金
国家自然科学基金资助项目(52168034)
宁夏自然科学基金资助项目(2023AAC03039)
宁夏高等学校一流学科建设(水利工程学科)资助项目(NXYLXK2021A03)
2024年宁夏大学研究生创新项目(CXXM202454)。
关键词
沙漠砂混凝土
硫酸盐冻融
单轴受压
峰值应力
声发射
desert sand concrete(DSC)
sulfate freeze-thaw
uniaxial compression
peak stress
acoustic emission(AE)
