The Research And Simulation On Control Techniques Of Temperature Crack In Massive Concrete Foundation

With the development of the science and technology, the massive concrete is more and more popular used during engineering construction period in modern times. For example, the container foundation in industrial and civil buildings , the dam in water conservancy and hydropower engineering and the rest pier in bridge engineering and so on. It pays more and more attention to control the temperature cracks in engineering field. At early age of construction and hardening of massive concrete structure, the unloading cracks in massive concrete structures are mainly caused by the thermal stress which due to hydration heat of cement, so this will threaten the integrity and the durability.At the present time, the measures to control the temperature cracks in massive concrete structure during construction period are mainly control the temperature of mixture placing to mold and the temperature difference of center and surface. For example, the measures such as placing phase I and II horizontal tubes with water during construction period, layered construction and installing deformation seam are based on the temperature difference of center and surface, and rarely take temperature and thermal stress double-control measures. Based on the double-control measures, this paper explores a new method to control the temperature cracks of massive concrete structure, this method combines the layered construction with placing vertical steel tubes. At first, it respectively analyses the effect of reducing temperature only by layered construction or placing vertical steel tubes by the basic theory of heat conduction, and provides the basis for the combination of both; and then studies the temperature field and stress field of massive concrete structure with vertical steel tubes during layered construction period by ANSYS finite element software, obtains that this method is useful; at last, obtains the steel tubes'specific effect of reducing temperature. Specific work of this paper is as follows:1. By reading a lot of data at home and abroad, describes the related theory of temperature cracks in massive concrete structure, and explains the common measures to control the temperature cracks in massive concrete structure.2. Introduces the basic theory of the temperature field and thermal stress in massive concrete structure, general mass concrete, in which highlights the distribution of the temperature field and thermal stress during construction period.3. Introduces the procedure and method of thermal analysis by the finite element, at first analyses the effect of reducing temperature only by layered construction or placing vertical steel tubes by related theory, and then respectively describes the way how to realize the simulation by ANSYS finite element software, and provides a theoretical basis for combination of layered construction and placing vertical steel tubes.4. Studies the temperature field and stress field of massive concrete structure with vertical steel tubes during layered construction period by ANSYS finite element software, obtains that this method is useful from temperature and temperature stress.5. Studies the temperature field and stress field of the same size of massive concrete structure without vertical steel tubes during layered construction period by ANSYS finite element software, by comparing with the temperature field and stress field with vertical steel tubes, obtains the steel tubes'specific effect of reducing temperature, and provides a further theoretical basis for combination of layered construction and placing vertical steel tubes.