Costruction Technology Of Temperature Control And Anti-cracking For RCC Gravity Dam Of Guandi Hydropower Station

Temperature control measures of RCC dam with relatively simple and rapid and continuous construction for its remarkable characteristics,but a large number of engineering practice at home and abroad show that the roller compacted concrete dam has also appeared many temperature cracks.The emergence and development of cracks leave hidden dangers for the safety operation of the dam.Therefore,how to take effective measures to control the temperature,which can make the roller compacted concrete dam can take thick concrete layer,short intermittent period and rapid construction method in construction process,and can ensure that the dam do not emerge temperature cracks in the construction and operation period,is one of the key technologies of continuous construction of roller compacted concrete dam throughout the year.This paper combines the Guandi Hydropower Station RCC gravity dam temperature control and crack prevention of concrete rapid construction technology for the following research:Firstly.Through the analysis of meteorological and hydrological data at the Guandi dam site,We know the difficulties about temperature control,mainly reflected in the following aspects:The climate in Guandi dam area is very dry all of a year,if the surface moisture is not enough,prone to produce large numbers of dry shrinkage cracks on concrete surface.In addition, due the dam site is located in the mountains,there is a large temperature difference between day and night,the maximum reached 20 degrees, the equivalent of a day through 20 degrees’ cold,Plus the crack resistance of roller compacted concrete itself is poor,and the bedrock strength is highly at the dam site,these objective factors results in temperature control and crack prevention of concrete during construction is very difficult.Secondly.Through control the quality of concrete raw materials strictly,to eliminate substandard materials put into the construction,ensuring the strength of concrete and avoiding cracks in the concrete structure.Thirdly.In view of the current situation the construction progress falls behind the schedule,proposing relative improvement measures,carring out the research on the scheme of fast construction scheme and its feasibility about dam concrete,aiming at achieving the purpose of continuous,high strength and rapid construction.Fourthly.aiming at the characteristics of complexity,specifieness and arduousness about Guandi Hydropower Station,The quality of the dam concrete is ensuresd through the adoption of the construction technology of temperature control and anti-cracking,.i.e.lowering the mixer outlet temperature of concrete,reducing the concrete temperature rise during transport and placement,controlling the maximum temperature of the dam body by cooling water and spraying chamber surface,etc.Finally.Through drilling core for the dam concrete,doing the experiment of water pressure,detecting temperature and observing the actual operation situation of the main part of the project in later period,evaluating the construction quality of Guandi dam.