Research On Construction Stratification Of RCC Gravity Dam In Yongdingqiao Reservoir

RCC dam construction is a kind of fast and efficient damming technology,as a result of its method embankment dam construction,the dam and monolith longitudinal seam cancelled,it already had casting large warehouse area and the fast construction speed.However,because of the influence of the cement hydration heat,mass concrete was casting pieces of size,slow cooling,temperature rising faster after cancel longitudinal seam,although relevant temperature measures from the design and materials aspect were taken,but the temperature control of mass concrete construction of RCC is still the key subject construction.Through Thickened the height of lift and decreased the number of layers,it can give full play to fast and efficient of the RCC construction,however,due to concrete dam layer thickness,concrete block is too large,the cement hydration heat release slowly,temperature rise too fast,the concrete does block high temperature stress and even produce temperature crack.Therefore,based on the requirements of temperature control,increase of RCC layer thickness is beneficial to improve the construction speed of RCC,shorten the construction period;Choosing the appropriate RCC layer thickness is unavoidable practical engineering problems.In this paper,as the example,yongding bridge barrage of reservoir resettlement which is pertain to the dadu river waterfall gully hydropower station in sichuang province.with the aid of ANSYS software platform,considering the changing of external environment,the parameters of the concrete material,and construction process factors and so on,2# dam began to simulate the temperature field from pouring to the construction completion,the whole construction process.Simulating the variation of temperature field and stress field of the 2# dam section of the Yongdingqiao Reservoir during the construction of layered casting process by using the thermal analysis module of ANSYS.Choosing four kinds of layering thickness to simulate according to the relevant literature and the experience of established engineering,such as 20 cm,30cm,35 cm and 40 cm,through the simulation calculation for four kinds of layered casting thickness of the dam’s concrte,the results can be expressed as follows:(1)Layering thickness of 20 cm meet the requirements of specification in the base temperature difference,internal and external temperature difference and the upper and lower temperature difference at different pouring height,but the longer construction period which is not conducive to control progress;Layering thickness of 35 cm and 40 cm do not meet the requirements of specification in addition to layering thickness of 30 cm,what’s more,layering thickness of 30 cm is conducive to control the construction period.(2)Based on the comparison and analysis of the first principal stress of each layering thickness,it can be concluded that the maximum value of the first principal stress meet the requirements of specification in the case of layering thickness of 20 cm and 30 cm;However,the maximum tensile stress of layering thickness of 35 cm and 40 cm exceeds the specification,which may produce cracks.(3)Through analyzing the temperature stress field of four kinds of layering thickness,20 cm,30cm,35 cm and 40 cm,the layering thickness of 30 cm is the optimal choice from the aspects of meeting the requirements of the specification and ttime limit for the project.