| The impact of temperature on mass concrete has always been the focus of attention in the construction industry at home and abroad.Especially,with the increasing of large span bridges,the internal temperature effect of the structure is becoming more and more thorough with the extensive application of mass concrete.But in the past studies are mainly for the concrete itself or internal factors of the analysis,which neglect the influence of many factors in the external environment on the internal temperature of the concrete.The neglect of these factors is likely to have an important influence on the temperature inside the concrete,and even lead to the increase of the temperature crack,thus destroying the stability of the concrete structure.This paper takes the main tower of the cable-stayed bridge of Yuejiang Bridge in Zhaoqing City,Guangdong Province as an example project.Based on ANSYS finite element software,the suitable unit type is selected,and the temperature field of the concrete construction platform is simulated and analyzed.The main research content has the following points:(1)According to the actual construction conditions,ANSYS finite element simulation is used to simulate the overall temperature field of the platform when the actual construction is carried out.The internal temperature field of the platform during pouring and the change of the temperature time course of different pouring nodes are analyzed.The trend of temperature change in the process of stratified pouring and the transverse and vertical temperature from the inside to the boundary of the platform are considered,using the simulation data and engineering measured data for comparative analysis.(2)Considering the influence of the external environmental factors on the internal temperature of the platform,the influence of the water level on the internal temperature of the platform during the change of the water level from the dry season to the wet period is studied.The influence of water level on the internal temperature field of the platform is analyzed.(3)The changes of the temperature field distribution in the platform are analyzed,and the change of the temperature and temperature difference between the nodes and the flow rate of the external fluid is studied emphatically.(4)The changes of the internal temperature field and the temperature gradient under different working conditions are studied under the conditions of external fluid temperature change,top surface water storage,side double thin wall steel cofferdam use,cooling water temperature change and so on.The following results can be obtained by the above analysis of the mass concrete cap: The peak number of the bottom node temperature curve is consistent with the number of pouring layers.The calculated data are consistent with the trend of the temperature time curve of the measured data,but the measured values are generally larger than the calculated values.As the water level rises,the internal temperature decreases,but the lateral temperature difference from the inside to the boundary increases gradually.With the increase of water velocity and wind speed,the internal temperature and temperature difference will decrease within a certain range of change.The external temperature changes on the internal temperature and temperature have an impact.With the outside temperature increasing,the internal temperature will rise but the temperature difference is reduced.Top-level water storage and double-wall steel cofferdam's usage will increase the temperature of the boundary position nodes,but can significantly reduce the temperature difference between the internal and the boundary.The temperature of the cooling water has obvious regulation effect on the internal temperature field.With the increase of the water temperature,the internal temperature also increases,but the temperature difference between the cooling pipe and the cap,both inside and outside,are reduced,which is beneficial to reduce the chance of the temperature crack. |
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