Discrete Element Analysis Of Freeze-thaw Mechanism Of Cement Concrete

Aiming at the damage problem of concrete structure in freeze-thaw environment,combined with the freeze-thaw mechanism of cement concrete,using discrete element method of discontinuous calculation of materials,a micro freeze-thaw damage model suitable for cement concrete is proposed,and the model is used to simulate Law of freeze-thaw damage of cement concrete under environmental factors.The core idea of ??the model is based on the freeze-thaw mechanism of micro-cement concrete.The PFC3 D software is used to define the pore water and cement material in the micro-structure of cement concrete.The freeze-thaw loading of cement concrete is simulated by simulating the freeze-expansion process of pore water.The model uses the parallel bonding model in PFC3 D software to consider the cementation between the material particles.In order to reflect the elastoplastic failure of cement concrete materials,the linear constitutive relationship of the parallel bonding model was modified to a non-linear curve relationship in the study to make the model loading results more accurate.This article mainly completed the following three items:(1)Simulated calculation of the freezing and thawing damage laws of C30,C40,and C60 cement concrete,which considered four environmental factors: cooling rate,minimum temperature,freezing time,and saturation level.The results of standard freeze-thaw tests and freeze-thaw tests under different influencing factors are presented.(2)Using the above multi-factor simulation results,through mathematical fitting analysis,the quantitative equivalent relationship between the standard freeze-thaw test and the actual environment freeze-thaw is proposed.(3)The C ++ platform was used to develop a small program of cement concrete freeze-thaw damage calculator.This program can not only query C30,C40 and C60 concrete freeze-thaw damage laws,but also be used to evaluate the concrete frost resistance level and predict the actual work under The service life of concrete.The research results in this paper show that the discrete element method has outstanding advantages in the calculation of freeze-thaw damage of concrete materials,and the results are accurate,which not only saves time and efficiency,but also breaks the conditions of traditional indoor freeze-thaw tests.The equivalent calculation relationship between the number of standard freeze-thaw tests and the actual environment freeze-thaw times providedin this paper can provide an important reference for the research of freeze-thaw damage of cement concrete and the evaluation of the freeze-thaw effect of actual projects.