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短期持压荷载与混凝土内水分传输的耦合过程
作者:鲍玖文 王立成 程宝娟 
单位:大连理工大学海岸和近海工程国家重点实验室 辽宁 大连 116024 
关键词:毛细吸水 持压荷载 体应变 累积吸水量 吸水率 
分类号:TU528
出版年,卷(期):页码:2016,44(8):0-0
DOI:10.14062/j.issn.0454-5648.2016.08.17
摘要:

荷载与环境因素的耦合作用影响着混凝土内物质传输过程和混凝土结构的服役寿命。为实现短期持续加载和混凝土内水分传输的耦合作用,基于改进的混凝土吸水实时测量装置,对中空圆柱体混凝土试件持续受压加载32 h的同时,按规定时间间隔记录水平观测管内水柱长度的变化,测得混凝土累积吸水量曲线,开展了短期持压荷载作用下低应力水平(0~50%)对混凝土毛细吸水性能影响分析,并根据试验结果建立了相对吸水率与体应变关系。基于扩展Darcy定律的非饱和流体理论(UFT model),采用指数和幂函数两种形式的水力扩散系数,开展了不同应力水平下混凝土中水分分布的预测分析。结果表明:短期持压荷载对混凝土的毛细吸水性能影响显著;在一定应力水平范围内,随着应力水平的提高,混凝土的累积吸水量和初始吸水速度先减小后增大,而后期吸水率和水分侵入深度却单调增加;根据UFT模型计算的水分渗透深度预测值与实际观测值吻合较好。
 

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Mass transport process and service life of concrete structures are affected by the coupling of loading and environmental conditions. In order to realize the coupled effect of short-term sustained loading and water absorption process within concrete, the capillary absorption of the hollow cylinder specimens at different compressive stress levels for 32 h was investigated by an improved device for timely measurement of cumulative absorbed water. According to the cumulative water absorption curve measured by the water length variation through the horizontal observed tube, the effect of low stress levels (i.e., 0–50%) on the capillary absorption in concrete subjected to short-term sustained loadings was analyzed. The linear quantitative relationship between the relative sorptivity and volumetric strain was discussed based on the experimental results. According to The water content distribution of concrete at various stress levels was predicted by two hydraulic diffusivity functions, i.e., the exponential-law and power function, based on the unsaturated flow theory (UFT) model of extended Darcy law. The results indicate that short-term sustained compressive loadings have a great influence on the capillary absorption of concrete. In the range of stress levels, the cumulative water content and initial water absorption rate initially decrease and then increase, and the secondary sorptivity and water penetration depth monotonously increase with the increase of stress level. Moreover, the predicted data of water penetration depth obtained by UFT model are similar to the experimental results.
 

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基金项目:
国家自然科学基金面上项目(51378090);国家重点基础研究发展计划(973计划)( 2015CB057701;2015CB057703)。
作者简介:
鲍玖文(1989—),男,博士研究生。
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