日温差对碾压混凝土大坝表面温度应力影响分析  

Analysis of the Influence of Daily Temperature Difference on Surface Temperature Stress of Compacted Concrete Dam

作　　者：王伶俐 任喜平 Wang Lingli;Ren Xiping(Xi'an Siyuan College,Xi'an 710038,Shaanxi;Hanjiang-to-Weihe River Water Diversion Project Construction Co.,Ltd.,Xi'an 710010,Shaanxi)

机构地区：[1]西安思源学院,陕西西安710038 [2]陕西引汉济渭工程建设有限公司,陕西西安710010

出　　处：《陕西水利》2023年第7期1-4,8,共5页Shaanxi Water Resources

基　　金：2012年陕西省水利科技计划项目(2012slkj-30);2016年陕西省水利科技计划项目(2016slkj-6)

摘　　要：碾压混凝土结构在施工期受温度应力的影响容易产生裂缝,大多情况下对混凝土大坝施工期的温控分析选取月气温变化,而本文对于引汉济渭三河口碾压混凝土薄拱坝选取日温差进行研究更趋合理,能为该地区同类坝型的设计和施工提供一定参考作用。依据秦岭南北分界区域特殊气候特征,建立三维有限元模型,分别取日温差为10℃、15℃、20℃进行计算坝体混凝土计算不同龄期、不同保护标准的温度应力,结果显示:在碾压混凝土施工期当地气候的温差降幅比较大的情况下,坝体混凝土龄期较长则自身混凝土产生的应力也会相应增大,同时在坝体表面或外漏面产生较大拉应力,在日温差降幅15℃和20℃时达到7d龄期的混凝土大坝表层产生的温度应力分别为0.533MPa和0.71MPa,超过混凝土的允许拉应力,采取等效放热系数为7kJ/(m^(2)·h·℃)5kJ/(m^(2)·h·℃)聚苯乙烯材料保护后坝体表面温度应力大幅减小,等效放热系数越小相应的温度应力降幅越大。Compacted concrete structure in the construction period by the influence of temperature stress is easy to produce cracks,in most cases on the concrete dam construction period of temperature control analysis to select the monthly temperature change,and this paper for the Introduction of Hanji W eihekou compacted concrete thin arch dam to select the daily temperature difference is more reasonable,can provide a certain reference for the design and construction of similar dams in the area.According to the special elimatic characteristics of the demarcation area between the north and south of the Qinling Mountains,a three--dimensional finite element model is established,and the daily temperature difference of l0C,15C and 209 is taken to calculate the temperature stress of the dam concrete at different ages and different protection standards,and the results show that:in the case of a relatively large decrease in the temperature difference of the local climate during the construction period of compacted concrete,the stress generated by the concrete of the dam will increase accordingly,and the tensile stress will be generated on the surface of the dam or the leakage surface.The temperature stress generated by the surface layer of the concrete dam at the age of 7days 15C and 20C when the daily temperature difference drops by 159C and 209C is 0.533 MPa and 0.71 MPa,respectively,exceeding the allowable tensile stress of concrete,and the equivalent exothermie coffcientof7kJ/(m^(2)·h·℃)and 5kJ/(m^(2)·h·℃)polystyrene material is protected by the surface temperature stress of the dam is greatly reduced,and the smaller the equivalent exothermic coefficient,the greater the corresponding temperature stress decrease.

关 键 词：日温差 温度应力 保护标准 拉应力 

分 类 号：U441.5[建筑科学—桥梁与隧道工程]