Back Analysis Of Concrete Temperature Field In Construction Of Hydraulic Structure And Its Application

Concentrated on simulative analysis of 3-D temperature and stress fields of mass concrete in hydraulic structure, back analysis of characteristic parameters of concrete temperature, feedback analysis and the application to practical project, the mainly work in this dissertation are discussed as follows:Firstly, according to the characteristics of mass concrete constructed with multi-layers and multi-blocks, a multi-laminate element model are proposed in FEM simulative calculation. By using the element model, the scale of FEM calculation is essentially reduced and the calculation efficiency is greatly increased on condition that the calculation precision is ensured. A special simulative program of 3-D FEM is designed and implemented based on the above methods.Secondly, the basic methods for parameter identification and the identifiability of parameter identification are dissertated. Through the example of the problem of heat emission in one-dimensional infinite slab, the identifiability of thermodynamic parameter of concrete is proved theoretically.Thirdly, for some unknown characteristic parameters of concrete temperature, back analysis methods of analytic solutions and FEM solutions with optimal mathematic method are discussed. The methods above are compared and verified. A new effective back analysis method, flexible tolerance method, is proposed.Finally, for a practical project, an experiment of temperature field of a cubic concrete block is made on construction site and the back analysis for unknown parameters is carried out. On construction site, observation, back analysis and feedback analysis are done, the corresponding effective methods of construction and measures of heat preservation are put forward in time.