Study on the relationship between particle sphericity and physical properties of sand based on 3D printing technology
[Objective]Sand as a kind of granular material,shape is an essential factor affecting its stacking state and shear prop-erties,in order to investigate the influence of the particles'overall contour(sphericity)on the physical properties of the parti-cles.[Methods]Three kinds of complex shape particles and spherical particle models were randomly generated by using the spherical harmonic function,and the particle models were printed by 3D printing technology.Relative density tests and straight shear tests were performed with 4 kinds of printing particles to analyze the stacking state and mechanical properties of particles with different shapes.[Results]Analyzing the 3D particle shape parameters,it was found that the shape differences of complex particles were mainly reflected in the overall contour(the maximum difference of sphericity was 0.718,and the maximum differ-ence of roundness was 0.032).With the increase of sphericity,the maximum porosity ratio of the particles decreased from 1.843 to 0.803,the minimum porosity ratio decreased from 1.121 to 0.603,and the difference of ultimate porosity ratio decreased from 0.722 to 0.200,and it was easier to reach the dense stacking state under the condition of the same relative densities;under the condition of the relative densities at 0.5,with the increase of particle sphericity from 0.241 to 1,the peak shear strength of the specimen decreased gradually,the internal friction angle decreased from 44.6° to 33.4°,and there was a linear decreasing rela-tionship between the internal friction angle and sphericity.[Conclusion]The method of generating irregular particles using the spherical harmonic function is greatly efficient in terms of calculation and storage cost.Based on the present experimental data,the relationship equation between complicated particle shape parameters sphericity and shear property index is derived,which provides theoretical basis for considering the influence of sphericity in practical engineering strength design and numerical simula-tion calculation work.
3D printingparticle shapesphericityshear propertiesstacking statesandmechanical propertiesinfluence factor