Study On Fractal Characteristics Of Surface Crack Distribution In Concrete Under Uniaxial Compression

Concrete is one of the most important engineering materials in the field of civil engineering.Studying the distribution pattern of surface cracks in concrete has important theoretical significance for evaluating the degree of damage and safety status of concrete.Due to the irregular distribution and obvious nonlinear characteristics of concrete surface cracks,traditional mechanical analysis methods cannot accurately and quantitatively describe them.In view of this,in order to accurately describe the distribution law of concrete surface cracks,this article uses fractal theory to analyze the single fractal feature and multifractal feature of concrete surface crack distribution.Based on the fractal theory,through the uniaxial compression test and numerical simulation of concrete,the single Fractal dimension,multi fractal generalized dimension and multi fractal spectrum of concrete surface crack distribution were quantitatively calculated by MATLAB program,the fractal characteristics of concrete surface crack distribution under uniaxial compression were studied,and the distribution law of concrete surface crack under uniaxial compression was explored.Through uniaxial compression tests of concrete,the effects of factors such as coarse aggregate particle size,sample size,peak stress,peak strain,absorbed energy per unit volume,brittleness index,and stress level on the single fractal dimension,multi fractal generalized dimension threshold width,and multifractal spectrum characteristic parameters of concrete surface crack distribution were explored.The concrete uniaxial compression elastic fractal damage constitutive equation based on the single fractal dimension of surface crack distribution,the threshold width of multifractal generalized dimension,and the peak value of multifractal spectrum has been established,revealing the distribution law of concrete surface cracks.The results show that the distribution of surface cracks in concrete specimens increases with the increase of peak stress,peak strain,absorbed energy per unit volume,and stress level,including the single fractal dimension,the threshold width of multifractal generalized dimension,and the peak value of multifractal spectrum;It decreases with the increase of coarse aggregate particle size,sample size,and brittleness index.The distribution of surface cracks in concrete under uniaxial compression not only has single fractal characteristics,but also has multifractal characteristics.Through the finite element analysis of concrete uniaxial compression,the effects of factors such as coarse aggregate particle size,sample size,peak stress,peak strain,absorbed energy per unit volume,brittleness index,and stress level on the single fractal dimension,multi fractal generalized dimension threshold width,and multifractal spectrum characteristic parameters of concrete surface crack distribution were explored.The concrete uniaxial compression elastic fractal damage constitutive equation based on the single fractal dimension of surface crack distribution,the threshold width of multifractal generalized dimension,and the peak value of multifractal spectrum has been established,revealing the distribution law of concrete surface cracks.The results show that the distribution of surface cracks in concrete specimens increases with the increase of peak stress,peak strain,absorbed energy per unit volume,and stress level,including the single fractal dimension,the threshold width of multifractal generalized dimension,and the peak value of multifractal spectrum;It decreases with the increase of coarse aggregate particle size,sample size,and brittleness index.The distribution of surface cracks in concrete under uniaxial compression not only has single fractal characteristics,but also has multifractal characteristics.