寒潮作用下高海拔地区混凝土重力坝防裂措施研究

发布时间：2018-03-31 13:31

本文选题：混凝土重力坝　切入点：温度场　出处：《青海大学》2015年硕士论文

【摘要】：混凝土重力坝体积大、工期长,在施工期和运行期难免遇到气温骤降。在我国西部高海拔地区,昼夜温差大,常年气温偏低,冬季寒潮袭击频繁,温度的剧烈变化经常会使坝体表面出现较大的拉应力,当拉应力超过混凝土的极限抗拉强度时,坝体往往会出现裂缝,影响坝体的正常使用,甚至带来更大的危害。本文结合高海拔地区某混凝土重力坝,依托大型通用软件ansys,利用APDL语言编制了重力坝施工期温度场和温度应力的仿真计算命令流。编制程序过程中充分考虑了混凝土的浇筑温度、外界气温变化、混凝土的绝热温升、太阳辐射、混凝土的徐变和弹性模量随龄期变化等的影响,仿真得出寒潮作用下混凝土坝的温度场和温度应力变化,在采用不同的保温材料时,对坝体的温度场和温度应力场进行对比分析。计算结果表明:寒潮作用下,裸露的混凝土表面极易产生拉应力,浇筑在基岩上的坝体受到基岩的强约束作用,会产生很大的温度应力。表面采取保温措施后,混凝土与外界环境的热交换减弱,表面温度提高,内外温差减小,有效地减小了寒潮期间混凝土表面的温度应力。保温效果与外界环境变化、保温材料及其厚度有密切关系,合理的选择保温材料对减少裂缝的产生具有重要的意义。
[Abstract]:The concrete gravity dam is large in volume and long in duration, so it is inevitable to encounter a sudden drop in temperature during construction and operation. In the high altitude area of western China, the temperature difference between day and night is large, the annual temperature is low, and the winter cold wave attacks frequently. When the tensile stress exceeds the ultimate tensile strength of concrete, cracks will often appear in the dam body, which will affect the normal use of the dam body. This paper combined with a concrete gravity dam at high altitude, Based on ANSYS, the simulation calculation command flow of temperature field and temperature stress during gravity dam construction is compiled by using APDL language. In the process of compiling the program, the pouring temperature of concrete, the change of outside temperature and the adiabatic temperature rise of concrete are fully considered. Under the influence of solar radiation, creep and elastic modulus of concrete with age, the temperature field and temperature stress of concrete dam under cold wave are simulated. When different thermal insulation materials are used, The temperature field and the temperature stress field of the dam body are compared and analyzed. The results show that the exposed concrete surface is easy to produce tensile stress under the cold wave, and the dam body placed on the bedrock is strongly constrained by the bedrock. After taking heat preservation measures, the heat exchange between concrete and the outside environment will weaken, the surface temperature will increase, and the temperature difference between inside and outside will decrease. The thermal stress of concrete surface is reduced effectively during the cold wave. The insulation effect is closely related to the change of external environment, the insulation material and its thickness. It is of great significance to select the heat preservation material reasonably to reduce the cracks.
【学位授予单位】：青海大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TV642.4

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