Optimization Analysis And Research On High Arch Dam Closure Process

With the improvement in the theory and method of arch dam design recently,China has planned and constructed a series of high arch dams.Because the construction of high arch dam is characterized by having concrete casting and closure process done at the same time.the closure process of high arch dams has close relationships between the temperature control of mass concrete,the initially stress conditions of arch dam,the stress deformation distribution affected by construction process,the cantilever height of arch dam section and construction process.It should be paid attention on temperature control and transverse joints aperture of concrete lift while(super)high arch dams have its own features.On aspect of temperature control,it is not only required that arch closing temperature should be achieved by temperature control measures before closure process but also temperature gradient should be controlled along the vertical orientation of dams.On aspect of cantilever height control,the cantilever height is easily over-height which possibly causes high stress on the root of cantilever if the concrete casting arrangement is improper during construction period and also has an influence on transverse joints aperture effecting the irrigation ability for joints.As a consequence,it's essential to optimize the involved engineering problems on the course of high arch dam closure process.The research based on the existing engineering and test data of Wudongde Project selects three typical engineering problems in the process of joint closure.Optimized route and plans considering concrete temperature control,stress and deformation conditions during the construction have been raised up by FEM.The main contents and researches are as follows:(1)Optimization analysis on the height of grout compartmentReferring to the original plan about height of grout compartment,a comparison plan which aims at appropriately enhancing the grouting range of free zone is proposed.The research overall considers the whole process of concrete construction,temperature control and joint closure.The result shows that enhancing the grouting range tends to improve the constraint between sections of dams and it's feasible to enhance the height of grouting range of free zone if it's necessary to accelerate construction progress and simplify the grouting zone.(2)Spatially dynamic optimization analysis on height of cold zoneA research route about spatial of cold zone is proposed,sensitivity analysis on different height of cold zone has been done according to different typical zone of segment of dam such as base constraint area,free area and orifice constraint area.The analysis result shows that there is a decreasing trend of max stress within irrigated area when the height of cold zone becomes higher and the effect of the height of cold zone is limited within the weak constraint zone.A proposed cold zone height plan of Wudongde arch dam has been set up based on the computing results.(3)Personalized control for cantilever height of high arch damA research route of personalized control for cantilever height is proposed.The analysis comprehensively considers the control standard including highest temperature,max stress and transverse joints aperture.The simulation results show that the first principle stress grows with the cantilever height increasing.In addition,ambient temperature recharging is the possible reason why cantilever height affects transverse opening.The allowable max cantilever height for different typical height of 7#segment of Wudongde dam has been confirmed according to the evaluation criterion.