The Research On Early Thermal Stress Of Slab Turnout's Base Plate

Slab turnout by its very nature is a concrete structure, non-load cracking in early age is one of the main factors of damaging the durability of concrete structures, this thesis researched early temperature stress of slab turnout, and main tasks are as follows:First, this thesis briefly introduced the basics of thermodynamics, including the concept of temperature field, heat conduction differential equation, initial conditions and four boundary conditions. According to thermal conduction and the basic principles of finite element method, summarized the basic theory of finite element in analyzing three-dimensional transient temperature field of concrete structure. Taking into accounting creep, shrinkage and other factors, carefully investigated calculation methods of thermal stress of concrete.Second, according to the mechanical characteristics slab turnout, established entity model of slab turnout in calculating temperature stress, selected thermodynamic parameters and structural parameters under referencing large amounts of data, and established the corresponding calculation method.Third, using the established model and selected methods calculated early temperature and early thermal stress of slab turnout, and on this basis, solved common problems in base plate's concrete construction, including the external air temperature range of pouring the base plate's concrete, reasonable conservation methods, a reasonable curing time, then proposed some following views:when pouring the base plate's concrete, ambient temperature can be between 15-35℃; after pouring concrete, when the outside temperature is between 15℃～30℃, part conservation methods can be used, and if the outside temperature is outside this temperature range, the overall conservation methods must be used; after pouring concrete, when the outside temperature is not between 15-30℃, the concrete curing must begin, and concrete curing can start from the second day when the outside temperature is between 15-30℃.Finally, the results are compared with theoretical values and verify the correctness of the theoretical calculation.