Experimental Analysis And Engineering Numerical Calculation Of Adiabatic Temperature Rise Of Roller Compacted Concrete With Different Large Amounts Of Fly Ash

In hydraulic structures,the main cause of cracks is the temperature change caused by cement hydration reaction and the decrease of external temperature.The more serious problem is that the influence of temperature stress on the internal safety of the structure is far greater than other stresses.Therefore,the use of low cement content of high volume fly ash concrete can reduce the generation of hydration heat and prevent early cracking.In this paper,through the adiabatic temperature rise test,the characteristics of high volume fly ash concrete are further studied.A simple test model is established to simulate the early strength of different schemes and relevant literature is consulted.The optimal scheme is selected to simulate the relevant material parameters of temperature field and temperature stress field.The results are calculated by ANSYS finite element software,and the results are analyzed in practice Application significance in engineering.Adiabatic temperature rise is an important basic parameter for the calculation of temperature stress.Therefore,according to the specification,the mix ratio is selected to carry out the adiabatic temperature rise test of 50%,55%,and 60%fly ash mixed roller C25 concrete.Combining the respective calculation formulas of the adiabatic temperature rise,the final adiabatic temperature rise of the roller compacted concrete with the fly ash content of 50%,55%,and 60%are 22.162?,19.758?,and 17.934?,respectively.The function calculation relationship between the adiabatic temperature rise of the fly ash concrete with fly ash content shows that the fly ash content has a linear relationship with the adiabatic temperature rise.The larger the fly ash content,the smaller the adiabatic temperature rise,And the smaller the early hydration rate.Based on the data of adiabatic temperature rise and the corresponding mix proportion,the specific heat value and elastic modulus of different schemes are calculated by referring to the corresponding literature,and the axial compression simulation test is carried out by using ABAQUS software,and the early strength simulation value of large amount of concrete is obtained.The results show that the strength of the concrete in the forming period is small,and the strength of the concrete in the 28 days after forming meets the requirements of the code.With the increase of the amount of fly ash,the strength of the concrete decreases.According to the adiabatic temperature rise,inverse calculation parameters and corresponding engineering data of 50%fly ash RCC,the equivalent model of left guide wall section of a hydropower station is established by using ANSYS finite element analysis software,and then the three-dimensional finite element numerical calculation of temperature field and temperature stress in pouring stage and operation stage is carried out.The calculation results show the unstable temperature field of left guide wall section Compared with the temperature stress is relatively small,it can meet the safety requirements of the code.Therefore,the large amount of fly ash concrete has a very good effect on improving the internal early cracks,and has a positive effect on improving the durability and stability of the internal structure of the concrete.