摘要
盾构隧道管片混凝土的收缩会引起管片的变形与开裂。为减小管片混凝土的收缩,本文在恒温恒湿的养护条件下,对不同配合比的管片混凝土棱柱体展开收缩试验,研究了减缩剂用量对混凝土收缩率的影响,并通过对混凝土收缩率和龄期的关系进行非线性回归分析,得到了管片混凝土的指数型混凝土收缩预测模型。结果表明:掺入减缩剂能明显降低管片混凝土的收缩,随着减缩剂用量的增加,管片混凝土的收缩速率降低,极限收缩应变减小,当减缩剂用量为2%时,对管片混凝土的收缩抑制效果最为明显,混凝土的后期收缩值减少约40%;指数型混凝土收缩预测模型能较好地反映混凝土的实际收缩性能,随着龄期的增加,其预测精度在不断提高,混凝土的实际收缩值与预测值之间的差值也在逐渐减小,当混凝土的龄期达到153 d时,两者之间的差值在5%以内。
The shrinkage of concrete in shield tunnel segments can cause deformation and cracking of the segments.To reduce the shrinkage of pipe concrete,this paper conducts shrinkage tests on different mix proportions of pipe concrete prisms under constant temperature and humidity curing conditions and studies the effect of the amount of shrinkage-reducing agent on the shrinkage value of concrete.It conducts a nonlinear regression analysis on the relationship between concrete shrinkage value and age to obtain a shrinkage prediction model for pipe concrete.The results show that adding a reducing agent can significantly reduce the shrinkage of concrete segments,With the increase of the shrinkage-reducing agent used,the shrinkage rate of concrete segments decreases,and the ultimate shrinkage strain decreases.When the amount of shrinkage-reducing agent is 2%,the shrinkage inhibition effect on concrete segments is most obvious,and the later shrinkage value of concrete segments decreases by about 40%;the concrete shrinkage prediction model can predict the shrinkage value of concrete well.As the age increases,the difference between the actual shrinkage value of concrete and the expected value gradually decreases.When the concrete age reaches 153 days,the difference between the two is within 5%.
出处
《混凝土世界》
2024年第6期55-59,共5页
China Concrete
关键词
管片混凝土
混凝土收缩
试验分析
Segment concrete
concrete shrinkage
experimental analysis
