基于温度历程因子影响的混凝土空间收缩历程模型研究  

Research on the spatial shrinkage history model of concrete based on temperature history factor

作　　者：高强 韦强 钟孟君 韦昱呈 陈亮胜 陈正[2] 李静 吴昌杰 GAO Qiang;WEI Qiang;ZHONG Mengjun;WEI Yucheng;CHEN Liangsheng;CHEN Zheng;LI Jing;WU Changjie(Guangxi Road Construction Engineering Group Co.,Ltd.,Nanning 530001,Guangxi,China;Key Laboratory of Disaster Prevention and Structural Safety of the Ministry of Education/Guangxi Key Laboratory of Disaster Prevention and Structural Safety,Guangxi University,Nanning 530004,Guangxi,China)

机构地区：[1]广西路建工程集团有限公司,广西南宁530001 [2]广西大学土木建筑工程学院省部共建特色金属材料与组合结构全寿命安全国家重点实验室,广西南宁530004

出　　处：《水利水电技术(中英文)》2024年第11期188-201,共14页Water Resources and Hydropower Engineering

基　　金：广西杰出青年科学基金项目“高原环境桥梁工程高韧性混凝土”(2022GXNSFFA035035)。

摘　　要：【目的】目前工程中对大体积混凝土的开裂风险评估主要考虑温度应力,且视混凝土整体均匀收缩。由于该类结构的非均匀温度场对混凝土收缩的影响,其内部各个部位的收缩发展并不均匀,导致开裂风险被低估。为更好地预测与评估开裂风险。【方法】通过分布式光纤实测了某拱桥基础大体积混凝土的温度历程和变形历程。据此以温度历程为参数提出了温度历程因子,并建立了考虑温度历程因子的面内大体积混凝土收缩计算模型。随后通过有限元计算分析了分别采用该模型的面内收缩与规范的均匀收缩后混凝土的最大拉应力发展差异。【结果】光纤实测结果显示:基础混凝土中心处温度较高,收缩早期发展迅速,于3.4 d发展至终值的80%,但收缩终值较低,仅330με;温度较低的边缘处收缩发展较缓,直到13.3 d才达到80%,但收缩终值较高,达到了470με。有限元计算结果显示:差异性收缩工况的早期最大拉应力虽然较低,但最终最大拉应力比均匀收缩由5.85 MPa提升至7.42 MPa,提升了26.8%。【结论】结果表明:大体积混凝土内部和表面的温度历程差异显著影响收缩发展;早期混凝土中心收缩发展迅速且收缩值大,而外部混凝土收缩发展缓慢且收缩值小,缓解了温度梯度带来的拉应力并导致早期开裂风险被高估;随后混凝土中心收缩发展停滞,而外部混凝土收缩持续发展逐渐超过中心,则加剧了温度梯度带来的拉应力并导致后期开裂风险被低估。研究结果对大体积混凝土开裂风险评估具有指导意义。[Objective]The current cracking risk assessment of mass concrete in engineering focuses on temperature stress and assumes that the overall concrete is uniformly shrinking.However,due to the influence of the non-uniform temperature field of mass concrete on its shrinkage development,the shrinkage development and distribution within is not uniform,leading to an underestimation of the risk of cracking.In order to better estimate and predict the risk of cracking,[Methods]the distributed optical fiber is utilized to measure the temperature and deformation history of mass concrete in an arch bridge foundation.Based on this,the temperature history factor is proposed,and the calculation model of in-plane mass concrete shrinkage considering temperature history factor is established.Then,the difference in maximum tensile stress development between this shrinkage model and the uniform shrinkage model adopted by existing specification is analyzed through finite element calculation.[Results]The measured result indicate that the temperature of the core foundation exhibits elevated levels,while the shrinkage progresses rapidly during the initial phase,achieving 80%of its ultimate value within a span of 3.4 days.However,the final shrinkage value is relatively low at only 330με.On the contrary,the temperature is lower and the shrinkage development is slower at the edge of the foundation,taking 13.3 days to reach 80%but result ing in a higher final shrinkage value of 470με.The result of the finite element calculation indicate that,despite the low initial maximum tensile stress under differential contraction conditions,there is a subsequent increase in the final maximum tensile stress by 26.8%from 5.85 MPa to 7.42 MPa,when compared to uniform contraction conditions.[Conclusion]The findings indicate that the disparity in temperature history between the internal and external regions of mass concrete significantly influences the progression of shrinkage.In the initial stage,the shrinkage of center undergoes rapid development with

关 键 词：大体积混凝土 收缩 数值模型 开裂风险 温度应力 影响因素 

分 类 号：U416[交通运输工程—道路与铁道工程]