Research On Meso-level Numerical Simulation Of Concrete Mechanical Properties Based On Freeze-Thaw Damage Model

Concrete structures in severe cold areas suffer from freeze-thaw cycles all the year round,and the mechanical properties of concrete materials decrease,and the durability and service life of the structure are reduced.Therefore,studying the frost resistance of concrete has great practical application value to engineering.The main thing is to follow the reaction of the iron melting circles to understand the law of changing the mechanical properties of concrete objects and to create a cold melting effect.Concrete is a very complex material,and changes in microscopic properties have an inevitable effect on the mechanical properties of molten concrete.The paper first uses Python combined with Abaqus software to generate a two-dimensional concrete mesoscopic model,and conducts uniaxial compression tests on concrete after freezing and thawing cycles.The evolution law of the mechanical properties of concrete materials is studied,and the relative compressive strength is used as a variable to determine the relational formulas of the relevant parameters of the freeze-thaw damage model;Secondly,the freeze-thaw damage model is used to perform meso-scale numerical simulation of the mechanical properties of concrete to verify the rationality of the freeze-thaw damage model;Finally,by changing the parameters of the interface transition zone and the content of coarse aggregate,the influence of meso parameters on the mechanical properties of concrete damaged by freeze-thaw is analyzed.The conclusions are as follows:(1)Using the Monte Carlo method,a comparative study on the generation methods of random aggregates was carried out,and a feasible method for generating polygonal aggregates was proposed.On this basis,concrete is considered a single material,consisting of three stages of concrete processing,mortar and interface transition zone,and using Python language and Abaqus software to implement the secondary development of the finishing program.(2)The freeze-thaw damage model is used to perform meso-scale numerical simulation of the mechanical properties of concrete,and the result of numerical modeling are compared with experimental data.Comparative results show that the stress curve fits well during different cooling-thawing cycles,and the corresponding errors in the modulus of elasticity,compressive strength maximum compression stress are within 10%of this model.The modeling results show that as the number of freeze-thaw cycles increases,the density of the concrete decreases,the intermediate transition zone the mortar strength decreases,causing rapid expansion in the concrete damage.It grows slowly due to the destruction of concrete.(3)The principles of climate change isolation have improved the physics of the transition zone,increasing the tensile strength and tensile strength of concrete,although this has almost no effect on the tensile strength;the increase of aggregate content preventing concrete from cracking and increasing elastic strength,compressive strength and air pressure.As the freezing-melting rate increases.Compared with the 0.7 and 0.8 interfacial transition zone parameter ratio,when the coarse aggregate content is 40%and 50%,the interfacial transition zone parameter ratio is 0.9,the coarse aggregate content reduces the compressive strength and modulus of elasticity of concrete by 60%,the peak voltage and peak compressor voltage increase the slowest.Therefore,the mechanical properties of the internal conveying area are improved,the coarse aggregate content is increased,and the cold resistance of the concrete is improved.This paper analyzes the concept of cost reduction,and uses it to compare the essentials.The answer is very important when using concrete in real technology.