Effect Of Pile Foundation On Hydration Heat Of Mass Pile Caps

At present,the construction of civil engineering buildings tends to be large,and the use of mass concrete is becoming more and more common.However,during the construction process,large-volume concrete is not well controlled due to hydration heat,which may cause cracks in concrete.In the field of bridge engineering,it is particularly important to study the influence of temperature field of mass concrete on the safety and durability of structures.Based on the existing research results of large-volume concrete hydration heat problem,this paper proposes a pile foundation model which is different from the pile-free model used in traditional analysis,and uses the finite element software ANSYS to analyze the following problems:1.Comparing the pile model with the pile-free model,and discussing the influence of pile foundation on hydration heat;2.Reliability and accuracy of calculation analysis for pile model and pile-free model;3.Distribution of hydration heat temperature field and temperature stress field in a pile model;4.Based on the pile model,the influence of ambient temperature and variable cooling water temperature on the heat of hydration is discussed and the optimization scheme is put forward.The results show that:1.Pile foundation reduces the extreme value of hydration heat temperature and temperature stress,and the occurrence time of the extreme value is advanced;the influence of pile foundation on hydration heat problem is weakened with the increase of pile foundation distance;2.The temperature distribution of the model with piles is as follows: the center is high,the surrounding is low,and there is a regular radial distribution of low temperature around the cooling pipe and pile foundation.The distribution of temperature stress field is: the central is tension stress while the surface is compression stress,A large regular radial distribution of tensile stress around the cooling tube and the pile foundation,and the pile model can better simulate the actual situation;3.The higher the ambient temperature,the smaller the extreme temperature difference of the surface and exterior,and the later it appears;4.The bigger the temperature difference between cooling water and the maximum temperature of the cap,the smaller the extreme temperature and temperature stress.The earlier the temperature difference occurs,then the cooling effect is better.With the increase of the temperature difference,the gradient of the cooling effect decreases,and it didn't change when beyond a certain range.5.According to the research conclusions of this paper,the construction control optimization measures are as follows:1.In winter construction,effective thermal insulation and maintenance measures should be taken for the cap,and construction should be stopped under extreme low temperature weather;2.In the temperature control of cooling water,the difference between the outlet temperature of cooling water and the maximum temperature of the cap should be controlled in the range of 15-30 degrees Celsius.