| In recent decades,the roller compacted concrete dam has gradually entered people’s field of vision.The dam type has been promoted by the dam industry because of its advantages of fast construction speed and low hydration heat.Engineering practice shows that the RCC dam can not avoid the temperature crack problem as the normal concrete dam.After the cracks in the dam body are produced,the impermeability,durability and integrity are reduced,which will cause greater damage to the safety of the dam.Serious dam failure will occur,giving life and property to the downstream people.Brings great threats.The research found that the causes of RCC dam cracking are concrete weight,temperature stress,shrinkage and creep,concrete shrinkage,external constraints,etc.Temperature stress and shrinkage and creep are the main factors of concrete cracking,and reasonable control of concrete temperature stress to prevent dam Body cracking is essential.Therefore,the correct analysis of the variation of temperature field and temperature stress field of RCC dam is of great significance for temperature control and crack prevention of dam body.At present,many experts and scholars at home and abroad have focused on the research of temperature control and crack prevention mainly in some large-scale and extra-large projects.Although they have achieved fruitful research results,due to the investment conditions and the characteristics of their own temperature stress,small and medium-sized RCC dams are affected.The temperature control measures of some large dams are not suitable for small and medium-sized RCC dams.In fact,the problem of small and medium-sized dam cracks that are superior in quantity far exceeds that of some large dams,especially small and medium-sized dams in cold regions.Unfavorable external climatic conditions increase the difficulty of temperature control and crack prevention.Based on the analysis of the variation of the temperature stress field distribution of small and medium RCC dams in cold regions,this paper actively explores the temperature control and anti-crack combination measures applicable to small and medium-sized projects in the region.Through ANSYS finite element software simulation analysis,the concrete and death unit technology is used to simulate the concrete layered pouring construction process.The concrete temperature field calculation mainly considers the adiabatic temperature rise,the external temperature,the reservoir water temperature,the pouring temperature and other temperature control measures.The calculation of concrete stress field firstly uses the UPFs function of ANSYS to construct the concrete creep equation,and then uses the custom version of ANSYS to calculate the long-term stress field.The calculation mainly considers temperature load,concrete creep,MgO,water pressure,Factors such as the weight of concrete.Combined with a small and medium-sized RCC dam project in the cold area,the temperature control and anti-crack measures of the surface layer of the pouring layer,the MgO of the concrete and the surface insulation of the dam are analyzed.According to the simulation results of this paper,the following conclusions are obtained: the surface water flowing on the pouring layer can reduce the maximum hydration heat of concrete to about 2.3 °C,which is beneficial to reduce the temperature stress value at the joint surface;the external MgO can effectively improve the basic strong confinement zone and The temperature stress state of the downstream surface;surface heat preservation has obvious effect on preventing cracking of the dam body,but the heat preservation start time should be reasonably selected.The whole calculation considers the influence of various factors on the temperature stress during the construction process,and puts forward some economic and reasonable temperature control and crack prevention suggestions,which provides a reference for temperature control and crack prevention of small and medium RCC dams in cold regions. |
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