不同温控措施对大尺寸混凝土结构物抗裂效果的影响
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摘要
大跨桥梁下部结构如承台、桥墩的共同特点是3个维度尺寸大,混凝土内部绝热温度高。混凝土中心处最高温度甚至可达70℃以上,如果没有有效地控制好混凝土内部的最高温度、内外温差和表面与环境温差,往往可产生较大的温度应力,当温度应力大于混凝土的抗拉强度时,将导致混凝土结构表面开裂,影响桥墩的整体性和耐久性。已有的研究对大尺寸混凝土结构物的温控措施进行了大量的研究,均重点关注了降低最高温度、降低两类温差的方法和可采取的措施,未考虑这些方法或措施的实际效果。基于高速公路桥梁柔性墩实体段混凝土的工程实际,采用数值模拟的方法,研究分析了整体浇注、分层浇注和布置冷却水管等不同的施工方案及温控措施对桥墩混凝土抗裂效果的影响。结果表明,整体浇注混凝土时不论是否布置冷却水管,抗裂安全系数均不符合要求,仍然会产生温度裂缝;分两层浇注混凝土,抗裂安全系数较大,是合适的温控措施。对于混凝土桥墩而言,分层浇注时已能较好满足要求,尽管再布置两层冷却水管的效果更佳,但以施工便利和经济角度考虑,最合适的温控措施是分两层浇注混凝土并不布置冷却水管。
The common characteristics of substructure of long-span bridge, such as pile caps and piers, are that the large 3 D sizes and high internal insulation temperature of concrete. The maximum temperature of concrete center is up to 70 ℃. If the maximum internal temperature, the internal and external temperature difference and the temperature difference between surface and environment are not effectively controlled, the greater temperature stress could be produced. When the temperature stress is greater than the tensile strength of concrete, the cracks on the surface of concrete structure will induced and affect the integrity and durability of piers. The existing researches have done a lot of research on the temperature control measures of large-size concrete structures. The methods and measures for reducing the maximum temperature and 2 types of temperature difference are paid attention to, but the actual effects of these methods or measures are not considered. Based on the engineering practice of the concrete segments of the flexible piers of expressway bridge, the influence of different construction schemes and temperature control measures, such as integral pouring, layered pouring with cooling water pipes, on cracking resistance effect of concrete piers are analyzed by using numerical simulation method. The result shows that(1) If the concrete is poured in one time, whether or not there is cooling water pipe, crack safety factor does not meet the requirements and temperature cracks will still occur;(2) If pouring concrete in 2 layers, the safety factor of cracking resistance is larger, it is suitable temperature control measure. For concrete bridge piers, the layered pouring can meet the requirements well. Although the effect of the added 2-layer cooling water pipe is better, the most suitable temperature control measures are 2-layer concrete pouring without cooling water pipe considering construction convenience and economy.
The common characteristics of substructure of long-span bridge, such as pile caps and piers, are that the large 3 D sizes and high internal insulation temperature of concrete. The maximum temperature of concrete center is up to 70 ℃. If the maximum internal temperature, the internal and external temperature difference and the temperature difference between surface and environment are not effectively controlled, the greater temperature stress could be produced. When the temperature stress is greater than the tensile strength of concrete, the cracks on the surface of concrete structure will induced and affect the integrity and durability of piers. The existing researches have done a lot of research on the temperature control measures of large-size concrete structures. The methods and measures for reducing the maximum temperature and 2 types of temperature difference are paid attention to, but the actual effects of these methods or measures are not considered. Based on the engineering practice of the concrete segments of the flexible piers of expressway bridge, the influence of different construction schemes and temperature control measures, such as integral pouring, layered pouring with cooling water pipes, on cracking resistance effect of concrete piers are analyzed by using numerical simulation method. The result shows that(1) If the concrete is poured in one time, whether or not there is cooling water pipe, crack safety factor does not meet the requirements and temperature cracks will still occur;(2) If pouring concrete in 2 layers, the safety factor of cracking resistance is larger, it is suitable temperature control measure. For concrete bridge piers, the layered pouring can meet the requirements well. Although the effect of the added 2-layer cooling water pipe is better, the most suitable temperature control measures are 2-layer concrete pouring without cooling water pipe considering construction convenience and economy.
引文
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[9]汪建群,方志,刘杰.大跨预应力混凝土箱梁水化热测试与分析[J].桥梁建设,2016,46(5):29-34.WANG Jian-qun,FANG Zhi,LIU Jie.Measurement and Analysis of Hydration Heat of Long Span PC Box Girders[J].Bridge Construction,2016,46(5):29-34.
[10]SONG X M,MELHEM H,LI J,et al.Effects of Solar Temperature Gradient on Long-span Concrete Box Girder during Cantilever Construction[J].Journal of Bridge Engineering,2016,21(3):1-16.
[11]朱伯芳.大体积混凝土温度应力与温度控制[M].北京:中国电力出版社,2012.ZHU Bo-fang.Temperature Stress and Temperature Control of Large Volume Concrete[M].Beijing:China Electric Power Press,2012.
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[14]吴六政.混凝土箱梁桥温度场的模拟[J].公路交通科技,2011,28(10):65-69.WU Liu-zheng.Simulation of Temperature Field of Concrete Box-girder Bridge[J].Journal of Highway and Transportation Research and Development,2011,28(10):65-69.
[15]刘扬,肖新辉.寒流作用下钢管混凝土高墩温度场观测与效应分析[J].公路交通科技,2011,28(7):61-66.LIU Yang,XIAO Xin-hui.Observation and Analysis of Temperature Effect of CFST High-rise Pier under Cold Current Effect[J].Journal of Highway and Transportation Research and Development,2011,28(7):61-66.
[16]叶见曙,雷笑,王毅.基于统计分析的混凝土箱梁温差标准值研究[J].公路交通科技,2009,26(11):50-54.YE Jian-shu,LEI Xiao,WANG Yi.Study of Characteristic Value of Thermal Difference of Concrete Box Girder Based on Statistical Analysis[J].Journal of Highway and Transportation Research and Development,2009,26(11):50-54.
[17]叶见曙,贾琳,钱培舒.混凝土箱梁温度分布观测与研究[J].东南大学学报:自然科学版,2002,32(5):788-793.YE Jian-shu,JIA Lin,QIAN Pei-shu.Observation and Research on Temperature Distribution in Concrete Box Girders[J].Journal of Southeast University:Natural Science Edition,2002,32(5):788-793.
[18]王毅,叶见曙.混凝土箱梁悬臂施工中温度梯度对标高影响的分析与控制[J].公路交通科技,2009,26(8):89-93,98.WANG Yi,YE Jian-shu.Analysis and Control of Temperature-gradient's Influence on Formwork Erection Elevation during Balanced Cantilever Cast-in-place Segmental Construction of Concrete Girder[J].Journal of Highway and Transportation Research and Development,2009,26(8):89-93,98.
[2]章征,王凯,李毓龙,等.混凝土桥墩施工期水化热及表面抗裂影响因素研究[J].桥梁建设,2015,45(2):65-70.ZHANG Zheng,WANG Kai,LI Yu-long,et al.Study of Influential Factors of Hydration Heat and Surface Cracking Resistance of Concrete Pier in Construction[J].Bridge Construction,2015,45(2):65-70.
[3]姜朔.特大桥实体桥墩水化热温度控制有限元分析[J].铁道建筑,2013(1):17-19.JIANG Shuo.Finite Element Analysis of Hydration Heat Temperature Control for Solid Pier of Super Large Bridge[J].Railway Engineering,2013(1):17-19.
[4]翟建平,秦红禧,何旭辉.铁路斜拉桥承台大体积混凝土水化热温度-应力场研究[J].铁道科学与工程学报,2011,8(2):27-33.ZHAI Jian-ping,QIN Hong-xi,HE Xu-hui.Study on Temperature-thermal Stress Field of Hydration Heat of Railway Cable-stayed Bridge Pile Cap[J].Journal of Railway Science and Engineering,2011,8(2):27-33.
[5]刘伟,殷国栋,刘开之,等.大体积混凝土承台水化热监控分析[J].公路,2014(2):39-42.LIU Wei,YIN Guo-dong,LIU Kai-zhi,et al.Analysis of Monitoring Hydration Heat of Large Volume Concrete Cap[J].Highway,2014(2):39-42.
[6]DE FREITAS J A T,CUONG P T,FARIA R.Modeling of Cement Hydration in High Performance Concrete Structures with Hybrid Finite Elements[J].International Journal for Numerical Methods in Engineering,2015,103(5):364-390.
[7]徐骏,江昔平,孟令飞,等.扬州商业广场筏板基础的温控措施[J].工业建筑,2013,43(11):92-95.XU Jun,JIANG Xi-ping,MENG Ling-fei,et al.Temperature-controlling Measures for Raft Foundation of Yangzhou Commercial Plaza[J].Industrial Construction,2013,43(11):92-95.
[8]吴献,穆春龙,张黎黎,等.筏板基础混凝土水化热研究及数值模拟[J].东北大学学报:自然科学版,2010,31(2):285-288.WU Xian,MU Chun-long,ZHANG Li-li,et al.Research on Concrete Hydration Heat in Raft Foundation and Numerical Simulation[J].Journal of Northeastern University:Natural Science Edition,2010,31(2):285-288.
[9]汪建群,方志,刘杰.大跨预应力混凝土箱梁水化热测试与分析[J].桥梁建设,2016,46(5):29-34.WANG Jian-qun,FANG Zhi,LIU Jie.Measurement and Analysis of Hydration Heat of Long Span PC Box Girders[J].Bridge Construction,2016,46(5):29-34.
[10]SONG X M,MELHEM H,LI J,et al.Effects of Solar Temperature Gradient on Long-span Concrete Box Girder during Cantilever Construction[J].Journal of Bridge Engineering,2016,21(3):1-16.
[11]朱伯芳.大体积混凝土温度应力与温度控制[M].北京:中国电力出版社,2012.ZHU Bo-fang.Temperature Stress and Temperature Control of Large Volume Concrete[M].Beijing:China Electric Power Press,2012.
[12]《建筑施工手册》第5版编委会.建筑施工手册[M].5版.北京:中国建筑工业出版社,2012.Editorial Board of the Fifth Edition of Construction Manual.Construction Manual[M].5th ed.Beijing:China Architecture and Building Press,2012.
[13]陈志坚,顾斌.大型混凝土箱梁水化热温度场的数值模拟[J].公路交通科技,2012,29(3):64-69.CHEN Zhi-jian,GU Bin.Numerical Simulation on Hydration Heat Temperature Field of Large-size Concrete Box Girder J].Journal of Highway and Transportation Research and Development,2012,29(3):64-69.
[14]吴六政.混凝土箱梁桥温度场的模拟[J].公路交通科技,2011,28(10):65-69.WU Liu-zheng.Simulation of Temperature Field of Concrete Box-girder Bridge[J].Journal of Highway and Transportation Research and Development,2011,28(10):65-69.
[15]刘扬,肖新辉.寒流作用下钢管混凝土高墩温度场观测与效应分析[J].公路交通科技,2011,28(7):61-66.LIU Yang,XIAO Xin-hui.Observation and Analysis of Temperature Effect of CFST High-rise Pier under Cold Current Effect[J].Journal of Highway and Transportation Research and Development,2011,28(7):61-66.
[16]叶见曙,雷笑,王毅.基于统计分析的混凝土箱梁温差标准值研究[J].公路交通科技,2009,26(11):50-54.YE Jian-shu,LEI Xiao,WANG Yi.Study of Characteristic Value of Thermal Difference of Concrete Box Girder Based on Statistical Analysis[J].Journal of Highway and Transportation Research and Development,2009,26(11):50-54.
[17]叶见曙,贾琳,钱培舒.混凝土箱梁温度分布观测与研究[J].东南大学学报:自然科学版,2002,32(5):788-793.YE Jian-shu,JIA Lin,QIAN Pei-shu.Observation and Research on Temperature Distribution in Concrete Box Girders[J].Journal of Southeast University:Natural Science Edition,2002,32(5):788-793.
[18]王毅,叶见曙.混凝土箱梁悬臂施工中温度梯度对标高影响的分析与控制[J].公路交通科技,2009,26(8):89-93,98.WANG Yi,YE Jian-shu.Analysis and Control of Temperature-gradient's Influence on Formwork Erection Elevation during Balanced Cantilever Cast-in-place Segmental Construction of Concrete Girder[J].Journal of Highway and Transportation Research and Development,2009,26(8):89-93,98.