Effect Of Particle Size Distribution And Shape On Minimum Void Ratio And The Shear Strength Of Sand

The minimum void ratio represents the most compact state of soil,which is closely related to the volume change trend and the shear strength of soil.The main influencing factors of the minimum void ratio and the shear strength of sand are the particle size distribution and the particle shape.Different particle size distributions and particle shapes would have direct impact on the internal structure of sand and bring about significant changes to its characteristics.In order to enrich the theoretical basis and provide relevant basis for evaluating the compactness and shear strength of sand foundation,it is necessary to conduct an in-depth research on related issues.Based on the minimum void ratio measurement test and the direct shear test,the effects of particle size distribution and particle shape on the minimum void ratio and shear strength of sand were explored.The main work and conclusions are as follows:(1)Measure the minimum void ratio of sand under different particle size distributions,and explore the influence of particle size distribution on the minimum void ratio.The results show that the minimum void ratio decreases with the increase of the particle size of the sand in the single-grain group;when two particles were mixed,the minimum void ratio decreases first and then increases.When the content of fine particles is about 40%,there is a minimum value of minimum void ratio in the variation curve.The smaller the ratio d/D of the mean particle size of the fine particles to the mean particle size of the coarse particles,the smaller the minimum void ratio.The larger the coefficient uniformity of sand,the smaller the minimum void ratio.Both the simulation results of particle flow code in three-dimension and the test results showed the same trend,which further confirmed the reliability of the test results.(2)Measure the minimum void ratio of four different particle shape sands,and explore the influence of particle shape on the minimum void ratio of sand.The results show that for a single particle group with the same particle size,the order of the minimum void ratio is closely related to the sphericity S of the particle.The larger the sphericity S is,the smaller the minimum void ratio.For the combination of sand and substitute particles,the larger the sphericity S of the particles,the smaller the minimum void ratio of the mixture.(3)Based on the direct shear test,the shear strength of the sand is measured,and the influence of the particle shape on the shear strength is studied by an alternative material.The results show that the shear strength of single-grain sand is closely related to the particle size.The larger the particle size,the higher the shear strength.The shear strength of sand after mixing two particles firstly increased and then decreased with the increase of the fine particle content.The more irregular the shape of the particles,the stronger the occlusal interlocking effect between the particles,and the stronger the ability of the soil structure to resist external force deformation.The minimum void ratio of sand is a characteristic parameter to investigate the shear strength of sand.