大体积混凝土温度裂缝的仿真分析及其控制
发布时间：2018-11-27 11:20
【摘要】：混凝土由于其强度高、耐久性好,被广泛用于各类建筑物、构筑物。随着工程技术的不断发展,各种新型、异型结构的不断涌现,大体积混凝土结构的运用越来越广泛。但大体积混凝土块体大,自身的导热性能较差,混凝土内部产生的水化热聚集难以发散,表面散热快,中心温度和表面温度的温差会造成混凝土裂缝；另外,弹性模量、松弛系数等也会随温度、时间的变化而变化,所以混凝土常常会开裂。如何控制大体积混凝土开裂,一直是结构和施工中的关键、难点。 本文在大量的实践基础上,总结了大体积混凝土的特点、混凝土开裂原因,并从设计和施工两个角度,分析了控制大体积混凝土开裂的有限措施。为真实反映工程的温度场和温度应力,本文采用大型有限元软件ANSYS,模拟分析了某县人民医院探伤室1#墙体温度场和温度应力,并得出以下结论：①一般情况下(无寒潮、气温骤降等情况),外界气温的变化对大体积混凝土温差影响不大,但对中心温度的影响较为显著；②浇筑温度越高,中心温度达到高峰的时间越短。 避免大体积混凝土开裂的措施很多,大部分研究学者都采用埋设冷水管的温控措施,但冷水降温不但会使混凝土内部受热不均匀,而且对本工程1~#墙体的防辐射不利,结合工程特点,1~#墙体将采用蓄水保温法的温控措施。 利用ANSYS仿真模拟大体积混凝土的案例很多,该类工程大部分都采用冷水管降温法,甚少采用蓄水保温法,将模拟分析与蓄水保温发结合的案例则更少。本文考虑大体积混凝土的中心温度、表面温度、水泥水化热、传热影响系数、龄期等因素,计算分析得出1~#墙体的蓄水保温厚度为：276mm,采取蓄水保温措施后,再用有ANSYS限元软件来模拟大体积混凝土的温度应力。经过模拟分析后,可以证实：混凝土各个点的应力值基本都在容许张拉应力之内,不会再出现裂缝。 除进行温控措施外,为能有效避免裂缝产生,本文将结合1~#墙体施工特点和工程的实际情况,从施工角度总结了大体积混凝土施工时的注意要点,例如：坍落度、雨季施上等问题。
[Abstract]:Because of its high strength and durability, concrete is widely used in buildings and structures. With the development of engineering technology, various kinds of new types and special-shaped structures are emerging, and the application of mass concrete structures is becoming more and more extensive. However, the mass concrete block is large, its thermal conductivity is poor, the hydration heat accumulation inside the concrete is difficult to disperse, the surface heat dissipates quickly, and the temperature difference between the center temperature and the surface temperature will cause the concrete crack. In addition, the modulus of elasticity and relaxation coefficient vary with temperature and time, so concrete often crack. How to control the cracking of mass concrete is always the key and difficulty in structure and construction. Based on a large number of practices, this paper summarizes the characteristics of mass concrete and the causes of concrete cracking, and analyzes the limited measures to control the cracking of mass concrete from the two aspects of design and construction. In order to truly reflect the temperature field and the temperature stress of the project, the temperature field and the temperature stress of the wall in the flaw detection room of a county people's hospital are simulated and analyzed by using the large-scale finite element software ANSYS, and the following conclusions are drawn: 1. The change of outside temperature has little effect on the temperature difference of mass concrete, but it has a significant effect on the center temperature. 2 the higher the pouring temperature, the shorter the time for the center temperature to reach the peak. There are many measures to avoid cracking of mass concrete. Most researchers have adopted temperature control measures for laying cold water pipes. However, cooling cold water will not only make the internal heat of concrete uneven, but also be unfavorable to the radiation prevention of the 1 # wall of this project. According to the characteristics of the project, the temperature control measures of water storage and heat preservation method will be adopted in the 1 # wall. There are many cases using ANSYS simulation to simulate mass concrete. Most of these projects adopt cooling method of cold water pipe, few of them adopt water storage and heat preservation method, and there are fewer cases of combining simulation analysis with water storage and heat preservation. In this paper, the central temperature, surface temperature, cement hydration heat, heat transfer coefficient, age and other factors of mass concrete are considered. The calculation and analysis show that the thickness of water storage and heat preservation of 1 # wall is 276mm. Then the thermal stress of mass concrete is simulated by ANSYS finite element software. After simulation and analysis, it can be proved that the stress values of each point of concrete are basically within the allowable tensile stress, and there will be no further cracks. In addition to temperature control measures, in order to avoid cracks effectively, this paper will summarize the main points of attention in mass concrete construction from the point of view of construction, such as slump, combined with the construction characteristics of 1 # wall and the actual situation of the project. Rainy season, etc.
【学位授予单位】：河北工程大学
【学位级别】：硕士
【学位授予年份】：2013
【分类号】：TU755.7
本文编号：2360556
[Abstract]:Because of its high strength and durability, concrete is widely used in buildings and structures. With the development of engineering technology, various kinds of new types and special-shaped structures are emerging, and the application of mass concrete structures is becoming more and more extensive. However, the mass concrete block is large, its thermal conductivity is poor, the hydration heat accumulation inside the concrete is difficult to disperse, the surface heat dissipates quickly, and the temperature difference between the center temperature and the surface temperature will cause the concrete crack. In addition, the modulus of elasticity and relaxation coefficient vary with temperature and time, so concrete often crack. How to control the cracking of mass concrete is always the key and difficulty in structure and construction. Based on a large number of practices, this paper summarizes the characteristics of mass concrete and the causes of concrete cracking, and analyzes the limited measures to control the cracking of mass concrete from the two aspects of design and construction. In order to truly reflect the temperature field and the temperature stress of the project, the temperature field and the temperature stress of the wall in the flaw detection room of a county people's hospital are simulated and analyzed by using the large-scale finite element software ANSYS, and the following conclusions are drawn: 1. The change of outside temperature has little effect on the temperature difference of mass concrete, but it has a significant effect on the center temperature. 2 the higher the pouring temperature, the shorter the time for the center temperature to reach the peak. There are many measures to avoid cracking of mass concrete. Most researchers have adopted temperature control measures for laying cold water pipes. However, cooling cold water will not only make the internal heat of concrete uneven, but also be unfavorable to the radiation prevention of the 1 # wall of this project. According to the characteristics of the project, the temperature control measures of water storage and heat preservation method will be adopted in the 1 # wall. There are many cases using ANSYS simulation to simulate mass concrete. Most of these projects adopt cooling method of cold water pipe, few of them adopt water storage and heat preservation method, and there are fewer cases of combining simulation analysis with water storage and heat preservation. In this paper, the central temperature, surface temperature, cement hydration heat, heat transfer coefficient, age and other factors of mass concrete are considered. The calculation and analysis show that the thickness of water storage and heat preservation of 1 # wall is 276mm. Then the thermal stress of mass concrete is simulated by ANSYS finite element software. After simulation and analysis, it can be proved that the stress values of each point of concrete are basically within the allowable tensile stress, and there will be no further cracks. In addition to temperature control measures, in order to avoid cracks effectively, this paper will summarize the main points of attention in mass concrete construction from the point of view of construction, such as slump, combined with the construction characteristics of 1 # wall and the actual situation of the project. Rainy season, etc.
【学位授予单位】：河北工程大学
【学位级别】：硕士
【学位授予年份】：2013
【分类号】：TU755.7
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