Simulation And Study On Temperature And Stress Fields For Mass Concrete Structure

The temperature and thermal stress fields analysis, the temperature control and crack control measures of the mass concrete structure are all important study subject in the design and construction, and the study on simulation calculations of the mass concrete structure temperature field and thermal stress field is of great practical significance. The thermal stress simulation computation is related with many factors, such as structural shape, the climate condition, construction process, material property and operation condition."Internal cooling and external heat insulation" is a common temperature control measure in the mass concrete construction. For the parts cast in high temperature season, or there being temperature requirement for the dam joint grouting, the water cooling measure is always adopted to reduce the peak temperature inside the dam, while for the parts cast in low temperature season or the dam encountering the cold wave, the superficial heat insulation measure is made to weaken the maximum temperature difference of dam surface, thus reducing the surface tensile stress. Therefore, the research on cooling pipe and superficial heat insulation are of great practical value. According to the heat conduction theory, mathematic model which can simulate the construction process is established, and it is posed that in the cooling areas, the cooling pipe substructure finite element method is used, while in other areas, the 3-D finite element relocating mesh method is utilized in the paper, and the study of coupling of substructure method and the 3-D finite element relocating mesh method is emphasized. Based on the heat budget theory, the temperature field finite element equation is deduced with thermal coefficient of conduction, surface thermal diffusivity and heat quality as basic parameters, so that it can reasonablely reflect the temperature field of composite structure composed of many materials of great different thermal properties. At the same time, the thermal coefficient of conduction method, the thermal diffusivity method and equivalent thickness method are all studyed.Regarding the actual situation that mass concrete is cast in layers and block to expand the dissipation areas and lessen the cast block size, the finite element model is established by Ansys software and it is posed to use the Fortran temperature control simulation programme to calculation the temperature field and thermal stress, then use the Surfer software to carry the postprocessing, thus making simulation calculation of any complex structure true. In the end, considering the problem that the indoor concrete test parameters can hardly reflect the ture property of the concrete in construction site, it is proposed that the 3-D finite element relocating mesh method and the flexible tolerance method are combined to inverse analyze the concrete thermal parameters, so as to get the ture concrete thermal property parameter for predicting and instructing the following construction.Through the research above, we can calculate the temperature field and thermal stress of the mass concrete structure with water cooling measure or surface heat insulation or by sequence placement, at the same time, the ture concrete thermal parameters can be defined by the observed temperature data in inverse analysis method, which provide the scientific references for the temperature field and thermal stress calculation of the mass concrete structure, and provide theory for the father study on the mass concrete temperature control.