Research Of FEM Algorithm For Temperature Field Of Composite Materials And Application In CFRD

Concrete faceplate is the crucial impermeable material of rock-fill dam, which means that stress and fracture analysis of faceplate is very important. A permeable faceplate will lead to bad operation of rock-fill dam. It is researched that thermal stress is the most important reason that results in the cracks of concrete faceplate. Thermal stress induced by temperature difference between day and night and cold current will bring on cracks of concrete faceplate that is directly exposed to the air, if there is no method of heat preservation before the arrival of winner. Therefore, study of heat preservation and preventing the appearance of cracks is absolutely necessary.The FEM equation for heat conduction which uses equivalent surface heat transfer coefficient as the primary parameter is used to calculate the heat preservation effect of heat preservation material that covers on the surface of concrete faceplate, while the traditional FEM equation which uses thermal diffusivity as primary parameter will lead to impractical result and can't reflect the true instance of heat conduction between many kinds of material with different qualities. Based the heat conduction equation, this paper makes an improvement on the original method by using thermal conductivity as the basic parameter of FEM algorithm for the temperature field. The calculation shows that, the improved FEM algorithm can be used to calculate the temperature field of heterogeneous or compound materials correctly.According to the construction schedule and local materials of the Jilintai CFRD in Xinjiang province, the temperature field and thermal stress of faceplate under the worst conditions are calculated with the improved FEM algorithm for the temperature field. Moreover, heat preservation effects of different thickness heat preservation materials on the surface of faceplates are calculated and analyzed. For the long faceplate, asphalt felt is laid between it and cushion. In the end, effects of measures above are compared.It is concluded that covering heat preservation material on the surface of concrete faceplate of CFRD can significantly reduce thermal stress of concrete. If the faceplate is long enough, it is necessary to lay asphalt felt that has small restraining force between faceplate and cushion besides covering heat preservation materials timely on the surface of faceplate to depress thermal stress of concrete faceplate effectively.