Study On Prediction Model Of Minimum Void Ratio Of Sand Binary Mixture Based On Particle Size Distribution And Particle Shape

The minimum void ratio is an important index to measure the compactness of sand accumulation structure,which is closely related to the deformation and mechanical properties of sand.In this study,the particle size distribution of natural sand is simplified,and the binary mixture formed by mixing two different particles is studied.The influencing factors of the minimum void ratio are analyzed to establish the prediction model of the minimum void ratio of binary mixture.The research contents and conclusions include the following points:(1)Three kinds of natural sands from different regions and substitute particles with more regular shapes are used as the research objects.The minimum void ratio of the binary mixture is determined by standard screening test and improved vibration compaction test.The experimental results show that the minimum value of the minimum void ratio(emin)min of binary mixtures,whether sand or substitute particles,decreases first and then increases with the increase of fine particle content(y2),and the minimum void ratio has a minimum value.At this time,the fine particle content is the optimal content(y2p),accounting for about 30%of the total mass of binary mixtures.(2)Based on the change law of the minimum void ratio of the binary mixture with the content of fine particles,the theoretical model of the network structure of the dominant particle network of the binary mixture is proposed.Based on the theoretical formula,the theoretical model for predicting the optimal content of the fine particles of the binary mixture is established.The comparison between the measured value and the predicted value proves that the model has high accuracy in predicting the optimal content value of the fine particles in the binary mixture.(3)The method to determine the overall shape parameters of natural sand and alternative particle mixture is proposed.It is clear that the sphericity plays a major role in the factors affecting the particle accumulation structure.The minimum void ratio of binary mixture is not only related to the particle size distribution,but also closely related to the particle shape.When the particle size distribution and the content of fine particles are the same,the shape of binary mixture particles is regular,and the minimum pore formed is relatively small.(4)The relationship among particle size distribution,particle shape and minimum value of the minimum void ratio is explored.A prediction model of minimum value of the minimum void ratio of binary sand mixtures is established.The study shows that there is an exponential function relationship between minimum void ratio(emin)min and particle size ratio d/D.Studies have shown that there is an exponential function relationship between(emin)min and d/D.In the model,the particle size ratio d/D is used to consider the effect of particle size distribution,and the functional relationship between the parameter T and the weighted sphericity of the binary mixture is used to consider the effect of particle shape.Comparing the measured minimum value of the minimum void ratio with the predicted value,it is found that the two values have a high degree of agreement.(5)The curve of binary mixture emin and y2 is simplified as a broken line.The inflexion coordinate is(y2p,(emin)min),point(0,e1)is the starting point of "V" curve,and point(1,e2)is the end point of "V" curve,where e1 and e2 are the minimum void ratios of coarse and fine particles respectively.The minimum void ratio of sand with arbitrary fine particle content can be estimated approximately by the broken line equation.So the prediction model of minimum void ratio of binary mixture based on particle size distribution and particle shape is established.The experimental results show that the prediction model has good applicability.