Study On Mass Concrete Surface Heat Preservation Caused By Cold Wave

The mass concrete structure with great size and complex structural patterns has many peculiarities. During the construction period, due to the heat generated by cement hydration, the internal temperature rises faster than the outside temperature, the expansion of mass concrete brings very large tensile stress on the structure surface; In late cooling process, the tensile stress will also exist, thanks to the constraint of the foundation, old concrete or the temperature gradient in concrete; the suddenly cold wave which cause the concrete surface temperature drop and a substantial contraction deformation, together with the nonequilibrium of the concrete construction and internal constraint, will result in large tensile stress. Particularly in cold areas, the concrete structure is exposed in the atmosphere; if any concrete surface heat preservation measures is not taken, the difference between day and night temperatures and the thermal stress caused by cold wave are very easily lead to concrete structures cracking. Therefore, the study of mass concrete surface heat preservation measures are extraordinary necessaryCurrently, to calculate the effects of the heat preservation layer, it is commonly used the simulation method of changing the surface heat release factor. However, when the heat preservation layer surface has the structure of the thermal insulation double deck or the material compositions exist large differences in performance, to mesh nets directly in heat preservation material can't reflect the nature of heat and material differences between the larger multiple heat conduction and the actual heat conduction nature of the larger variety of material differences. The results are often not rational. Based on calorie balance theory, the equative thickness method is used to simulating the heat preservation layer. The results show that this method can correctly calculate the effects of the heat preservation layer.In this paper, the RCC dam covered with heat preservation layer is studied. The original temperature field and temperature stress calculation procedure is amended so that it can reasonably reflect the temperature field and stress field of the dam consisting of different materials and with multiple structures. Based on an actual project, the temperature field and stress field of mass concrete structure under different temperature conditions is calculated.