Research On Calculation Method Of Temperature Field Of Concrete Dams On The Scale Level Of Cooling Pipes

Temperature control is the key concern during the construction phase of concrete dams, especially arch dams. The fine temperature field is the basis of intelligent temperature control, but existing researches cannot achieve the calculation of the real temperature field near cooling pipes without specially-modelled pipe elements or refined finite element meshes. This paper is to make systematic studies to fill this gap, and to propose a complete, fast, correct and engineering-objective simulation platform of mass concrete. The main contents and innovative points are listed as follows.(1) Based on the theory of partition of unity, the solution method of discontinuous concrete temperature field containing cooling pipes is proposed. The enrichment shape function is built upon the capture of nonlinear solution space by analytical solutions. The transformation method of the Dirichlet boundary condition is given, and the quadrature plan of discontinuous field and the discretion method of time domain have also been discussed.(2) The mesh-independent modelling method of cooling pipes is present. The fast searching and recognition method of 3D enriched elements and proposed to automate the modelling of cooling pipes based on computational geometry. The quadrature plan and correction method of boundary conditions are given including the oblique-cross, element-face-cross, and multiple-pipe-cross conditions. The calculation method of water temperature along the pipe is proposed on combination of analytical-solution method and numerical heat-transfer recursion method.(3) The thermal simulation platform of mass concrete is established. The equivalent thermal diffusivity is deduced by Mc Laurin series explansion based on the assumption of equivalent cooling model, and thermal simulation of massive concrete with different cooling-pipe-layout by only one mesh model. The Boolean-based external surface procedure method is proposed. The automatic post-processor of large engineering projects is developed, and the Internet-based visualization of scientific calculation is achieved.3D finite element program is developed, which can achieve the simulation of coarse-scale and fine-scale temperature field using the same mesh.