永定桥水库碾压混凝土重力坝施工分层研究

发布时间：2018-07-06 19:02

本文选题：碾压混凝土重力坝 + 施工分层　；参考：《华北水利水电大学》2017年硕士论文

【摘要】：碾压混凝土的施工是一种快速高效的筑坝技术,由于采用土石坝技术的施工方法,取消了坝体坝段的施工纵缝,浇筑仓面比较大,施工的速度较快;然而,大体积混凝土由于水泥水化热的影响,取消施工纵缝后,浇筑块的体积增大、散热缓慢、温度上升较快,尽管从设计及材料方面采取了相关的温度控制的措施,但大体积混凝土施工时的温度控制仍然是碾压混凝土施工的关键性课题。加厚铺筑层厚度,减少分层数量,可以充分发挥碾压施工的快速高效,但混凝土坝分层过厚,浇筑混凝土的块体过大,水泥水化热释放的缓慢,温度升高的过快,由于以上原因,可能导致混凝土坝体的温度应力太高,最终甚至会出现温度裂缝。因此,在满足温度控制要求的前提下,加大碾压混凝土分层厚度,有利于提高碾压混凝土的施工速度,缩短工期;选择合适的碾压混凝土分层厚度是实际工程中不可回避的问题。本文以四川省大渡河瀑布沟水电站移民安置项目永定桥水库拦河大坝为研究对象,借助于有限元仿真分析软件ANSYS为计算平台,对大坝2#挡水坝段从开始施工到施工完成的整个施工过程的温度场变化进行仿真模拟,综合的考虑了外界环境、混凝土材料参数、施工过程等因素在时间和空间中的不断变化。利用ANSYS中软件中的热分析模块和结构分析模块来进行仿真模拟永定桥水库2#挡水坝段施工期分层浇筑过程的温度场及应力场变化的全过程,根据相关文献和已建工程经验,选取20cm、30cm、35cm及40cm四种分层施工厚度进行仿真模拟,通过对坝体混凝土四种不同分层厚度的仿真计算,结果可以用以下几点表示:(1)20cm的分层厚度在不同施工高程处的基础温差、内外温差和上下层温差符合规范要求,但施工工期较长,不利于进度控制;35cm和40cm的分层厚度在不同施工高程处的基础温差、内外温差和上下层温差有一部分超出了规范要求;只有30cm的分层厚度在不同施工高程处的基础温差、内外温差和上下层温差满足规范要求,也有利于控制施工工期。(2)通过对各分层厚度第一主应力的比较分析,可以得出,20cm和30cm的分层厚度在不同施工高程处的第一主应力最大值都满足规范要求;35cm和40cm的分层厚度下最大拉应力超过了规范规定,可能产生裂缝。(3)通过对20cm、30cm、35cm及40cm四种分层施工厚度温度应力场的仿真分析,从满足规范要求和工期控制方面来考虑,30cm的分层厚度为本工程的最优分层厚度。
[Abstract]:The construction of roller compacted concrete is a fast and efficient dam construction technology. Because of adopting the construction method of earth-rock dam, the construction longitudinal joint of dam body section is cancelled, the storehouse surface is larger and the construction speed is faster; however, Because of the effect of cement hydration heat, mass concrete will increase in volume, slow heat dissipation and rapid rise in temperature when the longitudinal joint is cancelled, although the relevant temperature control measures have been taken in terms of design and materials. However, the temperature control of mass concrete construction is still a key issue in RCC construction. Thickening the layer thickness and reducing the number of layers can give full play to the rapid and high efficiency of roller compaction, but the layers of concrete dam are too thick, the concrete blocks are too large, the hydration heat release of cement is slow, and the temperature rises too fast. Because of the above reasons, the temperature stress of concrete dam may be too high, and even the temperature crack will appear. Therefore, under the premise of meeting the requirement of temperature control, increasing the delamination thickness of RCC is beneficial to improve the construction speed of RCC and shorten the construction period. It is an unavoidable problem in practical engineering to select appropriate thickness of RCC delamination. In this paper, the dam of Yongdingqiao Reservoir, a resettlement project of Pubugou Hydropower Station in Dadu River, Sichuan Province, is taken as the research object, and the finite element simulation analysis software ANSYS is used as the computing platform. This paper simulates the temperature field change of the whole construction process from the beginning to the completion of the dam section from the beginning to the completion of the construction. It synthetically takes into account the continuous changes in time and space of the external environment, the parameters of concrete material, the construction process and so on. The thermal analysis module and the structure analysis module in ANSYS are used to simulate the whole process of the temperature field and stress field change during the construction of Yongdingqiao Reservoir water retaining dam section during the construction period. According to the relevant documents and the experience of the built project, the whole process of the temperature field and the stress field change during the construction period of Yongdingqiao Reservoir is simulated. Four kinds of layered construction thickness of 20cm ~ (30) cm ~ (35 cm) and 40cm are selected for simulation and simulation. The results can be expressed as follows: (1) the temperature difference of 20cm's layered thickness at different construction elevation, through the simulation calculation of four different layering thickness of dam body concrete, The internal and external temperature difference and the upper and lower layer temperature difference meet the requirements of the code, but the construction period is longer, which is not conducive to the progress control of 35 cm and 40cm layer thickness in different construction elevation of the foundation temperature difference, some of the internal and external temperature difference and upper and lower layer temperature difference exceeded the requirements of the code; Only the layer thickness of 30cm can meet the requirements of the code at different height, and the difference of internal and external temperature and the temperature difference between upper and lower floors can also help to control the construction period. (2) through the comparison and analysis of the first principal stress of each layer thickness, It can be concluded that the maximum of the first principal stress of 20cm and 30cm layers at different construction elevations all meet the requirements of the code, and the maximum tensile stress under the delamination thickness of 35cm and 40cm exceeds the specifications. (3) through the simulation analysis of temperature stress field of 20cm ~ (30) cm ~ (30) cm ~ (-1) ~ (35) cm ~ (35) cm and 40cm, the optimum layering thickness of this project is considered from the aspects of meeting the requirements of specification and controlling time limit.
【学位授予单位】：华北水利水电大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TV544.921

【参考文献】