| A large number of project experience have shown that thermal stress and ice expansive pressure are the primary factors which cause mass concrete aqueduct to crack and wreck. Temperature fields do great effect on the stress and line deformation of the aqueduct. The ice expansive pressure is an especial issue which is caused by the variational temperature, and the ice cover will perform a pressure on the restriction. In some situation, the stress is large enough to threaten the safety of the structure.The project of South-to-North water transfer under construction is a great project, and the investments of the aqueducts are huge. So we should attach importance to the designs of huge aqueducts in order to ensure their credibility, economy and rationality. Since the thermal load and the ice load are two very disadvantageous factors sometime, we should do some study on them.On the basis of analyzing two kinds of loads above, this paper will make a research from three aspects as following.1. According to the examples of engineering practice, build up the three-dimensional model of aqueduct and then make programs to calculate the loss of prestressing force. The process of prestressed loading is optimized. The aqueduct structure can well satisfy the requirement of stress and deformation during construction period.2. With the finite element theory and the software ANSYS9.0, The aqueduct has been calculated, including the thermal field in the summer uniform temperature rise and solar radiation. Then the thermal-structure coupled-field analysis is used to calculate the stress.3. Using the ice creep model, this work deals with nonlinear solution of temperature and thermal stress field by the finite element method. Then calculate the thermal stress within the ice layer with two different methods and process the sensitivity analysis in allusion to the thickness of ice layer and the calefactive time. The result can provide valuable reference for the practical work.
|
PDF Full Text Request