钢管混凝土脱空机理分析-桥梁与隧道工程专业论文.docxVIP

摘 要 本文针对钢管混凝土脱空问题，从材料选择、养护环境与使用环境(主要为 温度变化)等方面着手展开系统研究，为解决实际工程所面临这一难题进行了攻 关。 首先，考察了水分对膨胀混凝土变形性能的影响。不同养护环境混凝土线膨 胀试验结果表明，非封闭养护环境下膨胀混凝土膨胀大；封闭养护环境下膨胀混 凝土膨胀小。封闭养护环境下，同种类陶粒混凝土线膨胀试验结果表明，存在最 佳陶粒掺量，掺50％鹤岗陶粒混凝土膨胀大、体积稳定性好；不同种类陶粒混凝 土线膨胀试验结果表明，吸水率大、粒径小、弹模高的陶粒混凝土膨胀大。得出 水分是影响核心混凝土膨胀的主要因素。 其次，考察了温度对钢管混凝土试件脱空的影响。钢管混凝土试件高、低温 循环试验结果表明，核心混凝土径向收缩随混凝土横截面积的增大而减小；核心 混凝土径向收缩随含钢率增大而增加；经历高、低温循环后，核心混凝土收缩大， 外钢管体积变化很小。 最后，考察了温度对钙矾石、延迟钙矾石的影响。对比不同养护环境水泥净 浆试样，经7天标养、3天高温(80。C)蒸养后恢复至室温(20℃)养护7天这一 过程，钙矾石及延迟钙矾石生成量，衍射试验结果表明，80。C蒸养3天后水泥净 浆试样中均出现大量稳定存在的单硫型水化硫铝酸钙(AFm)；再经20C养护7天， 封闭养护环境下水泥净浆试样中存在的延迟钙矾石(DEF)现象并不显著。 经理论分析认为荷载导致钢管混凝土弹性脱空理论值很小。 关键词：钢管混凝土脱空养护环境水分温度线膨胀钙矾石延迟钙矾石  摘要 AB STRACT The paper mainly analyses cavity problem ofconcrete—filled steel tube(CFST)．Deep researches are made on the choose of material、maintenance environment and exterior surroundings(mainly for changes of temperature)which help solving this kind of practical projects． First，the rule that moisture affects shrinkage and expansion of concrete is studied．The result of concrete linear expansion expriments in different maintenance environments shows that concrete expansion is larger in un-sealing treatment than in sealing treatment．In sealing treatment，the result of different kinds of haydite concrete linear expansion expriments shows that when water absorbency rate is large，haydite concrete expansion of small grain diameter and high elastic modulus is lareger．The result of the same haydite concrete linear expansion expriments shows that there exists best blending amount．Concrete expansion is large and volume stability is good in best blending amount．So moisture is the main factor which affects core concrete expansion． Second，the rule that temperature affects cavity of CFST specimens is studied．The result ofthe high and low temperature circulating expriments of CFST specimens shows that radial shrinkage of different crOSS sections in core concrete diminishes when crOSS sectional area grows large．Radial shrinkage of the same crOSS sectio