碾压混凝土重力坝温度应力分析

发布时间：2018-04-25 14:30

本文选题：碾压混凝土重力坝 + 温度场　；参考：《兰州交通大学》2017年硕士论文

【摘要】：碾压混凝土重力坝作为一种重要的大体积混凝土水工建筑物,在施工与蓄水过程中必须考虑温度应力问题。温度应力导致的裂缝会影响坝体的安全运行,而且在实际工程中温度场与应力场的变化规律又不尽相同,因此,温度应力的研究具有较高的科研价值及实用意义。本文建立某碾压混凝土重力坝三维有限元模型,根据碾压混凝土坝实际施工情况及运行资料,对其进行施工及蓄水全过程温度-结构耦合有限元计算分析,进行了下述研究:首先利用温度场有限元计算方法,考虑外界气温与水温、地基初始温度、水泥水化热及初始浇筑温度等因素的影响,分别得到自然浇筑温度、控制浇筑温度、自然浇筑温度+通水冷却三种方案下坝体施工结束时刻及蓄水结束时刻坝体温度场的分布规律,对三种方案的温度场分布规律及坝体特征点的温度历时曲线进行比较,分析了各种措施对温度场变化的影响。且将三种方案下的计算基础温差与规范规定的允许温差比较,可以看出控制浇筑温度与自然浇筑温度+通水冷却两种情况均能满足温控要求。根据特征部位的最大温度包络线说明了三种方案能否满足温控要求。接着,根据三种方案特征部位的温度应力包络线与最大拉应力云图,分析了各方案降低温度应力的效果。接着,在控制浇筑温度场的基础上得到考虑徐变因素时坝体施工结束时刻及蓄水结束时刻三个不同方向的温度应力及第一主应力的分布规律,为了动态研究三个不同方向的温度应力导致裂缝发展的规律,对表面点与中心点的温度应力历时曲线进行了相关分析。对考虑徐变前后的同一节点计算所得温度应力曲线进行比较,分析了徐变对温度应力的影响。将考虑自重前后特征部位的温度应力值进行比较,表明自重减小温度应力的有利作用。最后分析了在自重、水压力、温度作用三者共同作用下坝体结构的应力分布规律。
[Abstract]:As an important mass concrete hydraulic structure, RCC gravity dam must consider the temperature stress in the process of construction and storage. The cracks caused by the thermal stress will affect the safe operation of the dam, and the variation laws of the temperature field and the stress field are different in the actual engineering. Therefore, the study of the temperature stress has higher scientific research value and practical significance. In this paper, a 3D finite element model of a roller compacted concrete gravity dam is established. According to the actual construction situation and operation data of the roller compacted concrete dam, the temperature-structure coupling finite element analysis of the construction and the whole process of water storage is carried out. The following studies are carried out: firstly, the natural pouring temperature and the control pouring temperature are obtained by using the finite element method of temperature field, considering the influence of the external temperature and water temperature, the initial temperature of the foundation, the heat of cement hydration and the initial pouring temperature, etc. The distribution law of the temperature field of the dam at the end of construction and the end of water storage under the three schemes of natural pouring temperature, water cooling, and the distribution law of temperature field of the three schemes and the temperature duration curve of the characteristic point of the dam body are compared. The influence of various measures on the temperature field is analyzed. By comparing the basic temperature difference between the three schemes and the allowable temperature difference stipulated in the code, it can be seen that both the controlled pouring temperature and the natural pouring temperature can meet the requirements of temperature control. According to the maximum temperature envelope of the characteristic parts, the three schemes can meet the temperature control requirements. Then, according to the temperature stress envelope and the maximum tensile stress cloud diagram of the characteristic parts of the three schemes, the effect of each scheme to reduce the temperature stress is analyzed. Then, on the basis of controlling the pouring temperature field, the distribution law of the temperature stress and the first principal stress in three different directions of the end time of dam construction and the end time of impoundment are obtained when the creep factor is taken into account. In order to dynamically study the law of crack development caused by three different directions of temperature stress, the curve of thermal stress duration between the surface point and the center point is analyzed. The effect of creep on temperature stress is analyzed by comparing the calculated temperature stress curves of the same node before and after creep. The comparison of the temperature stress values before and after considering the deadweight shows that the self-weight can reduce the temperature stress. Finally, the stress distribution law of dam structure under the action of gravity, water pressure and temperature is analyzed.
【学位授予单位】：兰州交通大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TV642;TV544.921

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