Study On Working Condition During Construction Period And Integral Degree Of Safety On JinPing Arch Dam

JinPing is a huge project located on Yalong River in China. Its dam is concrete arch dam with Max height of 305.0m, which surpass Ingury and Xiaowan, and will be the highest arch dam in the world. The aim of this dissertation is to study some key problems such as thermal stress, transverse joints status and integral degree of safety of this dam by means of finite element method and theoretical derivation.Arch dams are generally constructed as cantilever monoliths separated by transverse joints, and the joint grouting is followed from the bottom to top of dam. During construction period, the effects on stress and transverse joints of dam, under the changes of concrete material, structural system and load, is necessary to be studied. In particular, high arch dams are generally impounded ahead of dam completion for gaining benefit, but the transverse joints will be jam-packed by water pressure after impounding, which is disadvantage to joint grouting. Therefore, understanding the rule of the effect of impounded water level on transverse joints aperture and specifying allowable impounded water level before joint grouting become necessary.The following problems are focused on in this paper.1. Considering the relationship of heat conduction and heat convection in the system of metal or non-metal cooling pipe and concrete, equivalent adiabatic temperature rise was calculated with FEM, and influence of pattern of arrangement of pipes and cooling water temperature on effect of cooling pipe was studied by simulation analysis of a typical casting pour.2. A control program was developed for analysis of temperature field and stress field, which realized parameterization of model building and analysis process. Thus, the efficiency of using general FEM programs to solve engineering problems is enhanced.3. Taking into account joint grouting and impounding, the temperature field, stress field, and transverse joints aperture of JinPing arch dam duringconstruction period are predicted by simulation analysis, and some valuable results are obtained.4. The fact that the transverse joints will be jam-packed by water pressure after impounding is disadvantage to joint grouting. The formula of estimating close of transverse joints aperture under water pressure are deduced, based on the principle that crack width is the change of displacement.5. The transverse joints aperture under different impounded water level is predicted by simulation analysis, in order to demonstrate the effect of different impounded water level on transverse joint aperture, and the allowable impounded water level before joint grouting is proposed.6.Using three-dimensional nonlinear FEA and considering accumulative gravity and design water pressure as initial load, overload method and margin of safety method are adopted to analyze the failure process of JinPing arch dam, and the safety factors of integral stability and characters of failure are acquired.