大体积承台热力耦合分析及防裂研究

发布时间：2018-03-03 19:38

本文选题：大体积混凝土　切入点：承台　出处：《山东大学》2015年硕士论文　论文类型：学位论文

【摘要】：大体积混凝土构件在水利工程中具有广泛的应用,随着我国桥梁结构对跨越能力要求的提高,大体积混凝土构件越来越多的出现在桥梁工程建设中。桥梁工程与水利工程有所不同,大体积混凝土构件更多的以桥梁承台、零号块或者斜拉桥桥塔等结构形式出现。大体积混凝土构件在使用过程中需要克服的问题是其水化过程中易于开裂的特性,由于自身体积较大,在水化放热过程中会引起的较大的内外温差,如果控制不当很容易引起裂缝。裂缝会引起一系列次生病害,例如后期钢筋锈蚀、混凝土腐蚀、耐久性降低、寿命下降等等。本文以西部某120米主跨连续刚构桥为工程背景,以现场测试数据为基础,结合数值模型,对大体积混凝土承台温度效应规律进行分析总结。并以此为基础,对大体积混凝土温度场的各种影响因素进行分析研究。本文主要工作如下：1)首先列举了国内外学者对于混凝土水化热原理以及施工现场温度控制措施的研究现状,介绍了混凝土温度效应计算参数以及分析原理；分析混凝土徐变影响因素,给出常用的徐变预测模型。2)调查桥梁现场工程概况,给出现场地质水文资料、气象环境参数,为数值分析提供基础。测试承台水化热温度数据,结合数值分析结果,分析混凝土水化热分布规律,并检验数值模型的可靠性。3)通过现场数据测试,作出承台内部温度变化曲线,采集出水口温度变化规律并且对数据进行平滑处理,推导承台合理拆模时机计算方法。根据该计算方法提出承台合理拆模时机,为相同参数的后续承台施工提供参考。4)以数值模型为基础,开展参数分析,以通水流量、水温、水管管径等为分析对象,探讨其对混凝土温控效果的影响；分析混凝土浇筑温度变化和外部保温措施对于构件应力分布状态的影响,为现场温控措施提供参考。5)针对桥梁所在区域经常出现的寒潮和昼夜温差,开展参数分析,归纳总结寒潮强度以及对流系数与混凝土表面应力的关系。提出临界降温幅度和能够抵消寒潮不利影响的临界等效对流系数,为现场保温提供参考。
[Abstract]:Mass concrete members are widely used in water conservancy projects. More and more mass concrete members appear in the construction of bridge engineering. Structural forms such as zero block or cable-stayed bridge tower appear. The problem that mass concrete members need to overcome in the process of use is that they are prone to cracking during hydration, because of their large size, Large internal and external temperature differences during hydration and heat release can easily lead to cracks if they are not properly controlled. Cracks can cause a series of secondary diseases, such as corrosion of reinforcement in the later stage, corrosion of concrete, and reduced durability. Taking a 120m main span continuous rigid frame bridge in the west of China as engineering background, based on field test data and numerical model, the temperature effect law of mass concrete cap is analyzed and summarized in this paper. The main work of this paper is as follows: firstly, the research status of domestic and foreign scholars on the principle of hydration heat of concrete and the temperature control measures in construction site are listed. This paper introduces the calculation parameters and analysis principle of concrete temperature effect, analyzes the influencing factors of concrete creep, gives the commonly used creep prediction model. Testing cap hydration heat temperature data, combining the results of numerical analysis, analyzing the distribution law of concrete hydration heat, and checking the reliability of numerical model. According to the curve of inner temperature change of the cap, the rule of temperature change of the outlet and the smooth processing of the data, the calculating method of the reasonable time of removing the mould of the cap is deduced. According to the calculation method, the reasonable time of removing the mould of the cap is put forward. Based on numerical model, parameter analysis is carried out, and the effects of water flux, water temperature and pipe diameter on the effect of temperature control of concrete are discussed. This paper analyzes the influence of concrete pouring temperature change and external heat preservation measures on the stress distribution of concrete members, and provides a reference for the field temperature control measures. 5) in view of the cold wave and diurnal temperature difference that often occur in the bridge area, the parameter analysis is carried out. The relationship between cold wave intensity and convection coefficient and concrete surface stress is summarized. The critical cooling range and critical equivalent convection coefficient, which can counteract the adverse effects of cold wave, are put forward to provide reference for field heat preservation.
【学位授予单位】：山东大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：U445.57

【引证文献】