京张铁路超大断面隧道衬砌混凝土制备技术

摘要

According to the structure characteristics and environmental conditions of super-large cross-section tunnel lining in the Great Wall station of newly built Beijing-Zhang jiakou railway,the lining concrete with high f illing ability,low hydration heat,low shrinkage and high compaction was prepared by optimization of raw material and mix proportion,micro aggregate f illing,temperature-drying shrinkage compensation.The combination of self-adhesive moisture maintenance f ilm and inflatable air-f ilm was proposed as a new curing measure,which effectively avoided unavailable curing for lining concrete.The optimized mix proportion of concrete was applied to the Great Wall station.After optimization,the peak value of concrete temperature is 53.4 ℃.There is no cracking phenomenon of solid concrete at the age of 30 d.The permeability coeff icient of concrete is 0.24×10-16m2,which is only 12% of the pre-optimized concrete.%针对新建京张铁路长城车站超大断面隧道衬砌的结构特点和环境条件,通过优选原材料、优化混凝土配合比、微集料填充、温度收缩与干燥收缩补偿等途径,试验配制出高充填性、低水化热、低收缩和高密实的衬砌混凝土;提出了自粘式保湿养护膜与充气式气模相结合的新型养护措施,有效解决了衬砌混凝土养护不足的问题.采用优化后混凝土配合比在长城车站进行了试用,优化后混凝土温度峰值为53.4℃,30 d龄期时实体混凝土未出现开裂现象,混凝土气体渗透系数为0.24×10-16m2,仅为优化前混凝土的12%.