浇筑厚度、间歇时间对碾压混凝土重力坝温度和应力的影响研究

发布时间：2018-11-15 15:48

【摘要】：高坝混凝土浇筑用量大、施工强度岛、施工条件复杂,既要考虑导流、防洪渡汛、、施工环境等备个要素影响,又要考虑温度控制、结构应力等因素的影响,所以大型混凝土坝施工是一个非常重要而又复杂的过程。与此同时,为谋求提早蓄水发电效益,在实际水利工程施工中,混凝土施工中容易开裂,影响工程的安全,所以有必要分析影响混凝土施工中浇筑厚度和间歇期的因素,找到混凝土的快速浇筑的规律,为以后类似工程的温控设计提供借鉴和参考依据。本文建立了溢流坝三维有限元模型,研究了坝体在不同间歇时间、不同浇筑厚度条件下碾压混凝土坝的温度和应力的变化规律,研究结果表明:(1浇筑层厚越厚, 早期坝体内部最高温度越高。坝体不同区域最高温度不仅与浇筑厚度有关,也与浇筑季节密切相关,在低温季节浇筑的混凝土,浇筑层越厚,最高温度也越大。混凝土基础垫层区X、Y、Z方向拉应力随着浇筑厚度的增大而增大,三级配碾压混凝土区X、Y、Z方向拉应力随着浇筑厚度的增大增大,二级配碾压混凝土防渗层区X、Y,Z方向拉应力随着浇筑厚度的增大而减小,二级配常态混凝土 X、Y、Z方向拉应力随着浇筑厚度的增大而增大。(2) 当浇筑层厚不变时,随着间歇期越长,散热越充分,混凝土内部最高温度越低,坝体混凝土内外温差也就越小。混凝土基础垫层区间歇时间越长,X、Y、Z方向拉应力越大,坝踵部位处于应力集中状态:三级配配碾压混凝土区X、Y、Z方向拉应力随着间歇时间的增大而减小:二级配上游防渗层碾压混凝土区X、Y、Z方向拉应力随着间歇时间的增大而增大;二级配态溢流面混凝土X、Y、Z方向拉应力随着间歇时间的增大而减小。(3)最后以某工程为例,拟定了 7个方案进行快速施工温控研究,由计算结果可知:方案2、方案3、方案6和方案7能满足温度场和温度应力要求。但在采取相同的温控措施条件下,方案6的施工工期最短,大大加快了施工进度,这样既节省工程投资还能使工程提前发挥效益,因此,采纳方案6作为快速温控方案更为合理。
[Abstract]:The high dam concrete has the advantages of large amount of concrete pouring, construction intensity island and complex construction conditions. It is not only necessary to consider the influence of factors such as diversion, flood control, construction environment and so on, but also the influence of temperature control, structural stress and other factors. So the construction of large concrete dam is a very important and complex process. At the same time, in order to advance the benefit of water storage and power generation, in the actual water conservancy construction, the concrete is prone to crack, which affects the safety of the project, so it is necessary to analyze the factors that affect the pouring thickness and the interval period in the concrete construction. The rule of rapid pouring of concrete is found, which provides reference and reference for the temperature control design of similar projects in the future. In this paper, a three-dimensional finite element model of overflow dam is established, and the variation of temperature and stress of RCC dam under different intermittent time and different pouring thickness is studied. The results show that: (1) the thickness of pouring layer is thicker, The highest temperature in the early dam body is higher. The highest temperature in different regions of the dam is not only related to the pouring thickness but also to the pouring season. The thicker the pouring layer is, the higher the maximum temperature is during the low temperature season. The tensile stress in the direction of XFY _ (Z) direction increases with the increase of pouring thickness in the cushion area of concrete foundation, and the tensile stress in the direction of X _ (Y) _ (Z) direction increases with the increase of the thickness of pouring in the area of tertiary RCC, and in the zone of impermeable layer of secondary RCC, the tensile stress increases with the increase of pouring thickness. The tensile stress in YZ direction decreases with the increase of pouring thickness, and the tensile stress increases with the increase of pouring thickness in secondary normal concrete. (2) when the thickness of pouring layer is constant, with the increase of intermission time, The more sufficient the heat dissipation, the lower the maximum temperature of concrete and the smaller the temperature difference between inside and outside of dam. The longer the interval time in the cushion area of concrete foundation is, the greater the tensile stress is in the direction of XY, and the stress concentration in the dam heel is in the state of stress concentration. The tensile stress in Z direction decreases with the increase of intermittent time. The tensile stress in the direction of XY _ (Z) direction decreases with the increase of intermittent time. (3) finally, taking a project as an example, 7 schemes are worked out to study the temperature control of rapid construction. The calculation results show that: scheme 2, Schemes 3, 6 and 7 can meet the temperature field and stress requirements. However, under the same temperature control measures, the construction period of project 6 is the shortest, which greatly accelerates the construction progress, which not only saves the project investment but also makes the project benefit in advance. It is more reasonable to adopt scheme 6 as a fast temperature control scheme.
【学位授予单位】：西安理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TV544

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