Experiment And Research On The Influence Of Mineral Composition And Particle Size On Soil Mechanical Properties

Clay content has an important influence on the macroscopic physical and mechanical properties of soil,such as liquid-plastic limit,strength,seepage,and stability.At present,relevant domestic and foreign geotechnical codes divide soil particles into groups based on the geometric size of the particles.For example,Chinese codes often classify particles with a particle size of less than 5 ?m into clay groups.However,it is difficult to evaluate the properties of soil engineering based on the composition(proportion)of the particle group to divide the particle group based on pure geometric size.For example,tiny quartz particles do not show cohesion,but the friction effect is obvious;relatively large montmorillonite particles have significant cohesion and a very small internal friction angle.In order to comprehensively consider the influence of particle mineral composition and geometric size,my research team proposed the energy scale division criterion of particle size,which is based on the ratio of the microscopic force between particles(Coulomb force and van der Waals force)and particle gravity(microgravity).The size of particles can be divided into particle categories,and the boundary size of particles that produce cohesion and friction effects between particles can be determined.From the particle category,the impact on the engineering characteristics of the soil can be judged.At present,based on the assumption of spherical particles,the members of the team have studied the characteristics of the microgravity ratio of different minerals with the change of mineral composition and particle size;however,the calculated microgravity ratio cannot well reflect the mineral composition and particle size.The influence on the mechanical properties of cohesive soil;in addition,the microgravity ratio formula used only considers the effect of Coulomb force,not the effect of van der Waals force,and when the particle size is very small(at the nanometer level),van der Waals force The role of the impact is great and can not be ignored.This article will further study the influence of particle mineral composition and geometric size on soil mechanical properties on the basis of the predecessors,and then adopt a new calculation method(the original calculation method adopts electric double layer calculation,which can be called electric double layer method),Will calculate the microgravity ratio according to the flaky particle model and recalculate the microgravity ratio according to the spherical particle model,and consider the effects of van der Waals force and Coulomb force.Comparing the microgravity ratio calculated by the two models,the result is that the regularity of the energy scale is unchanged regardless of whether the flaky particle model or the spherical particle model is used.Comparing the formula derivation methods of spherical particles and flaky particles,it is found that the microgravity ratio calculated by the flaky particle model is easier and more accurate than the microgravity ratio calculated by spherical particles.The main research work and conclusions of this article are as follows:(1)Through experimental research,it is found that the three mineral components of similar geometric particle size are montmorillonite,illite and kaolinite soils with different plastic limit characteristics,permeability characteristics and strength characteristics.Mineral composition is the main factor that affects the engineering properties of the soil.The particle size of mineral particles also has a great impact on the properties of the soil.As the particle size decreases,the liquid plastic limit of the soil increases and the permeability coefficient It decreases accordingly,and under the same vertical load,as the particle size decreases,the shear strength of the soil increases.(2)Compared with the calculation of the original microgravity ratio,the microgravity ratio calculated again according to the spherical particle model can better illustrate the influence of mineral composition and particle size on the mechanical properties of cohesive soil.(3)The new calculation method is adopted,whether it is a flake particle model or a spherical particle model,the calculated microgravity ratio results show that unless the particle size is very small(nano-level)or very large(when the particle size is greater than 200 m),Otherwise the microgravity ratio of Coulomb force is much larger than that of van der Waals force,that is,the microgravity ratio of Coulomb force plays a controlling role.(4)Adopting the new calculation method,whether it is the flake particle model or the spherical particle model,the regularity of the energy scale is the same,that is,the microgravity ratio of different minerals changes in accordance with the relationship curve of the particle size,and the clay of different minerals has A good degree of discrimination can reasonably reflect the influence of particle size and particle mineral composition on the microscopic force.The flaky particle model formula is easier to derive than the spherical particle model,and the clay particles are generally flaky,so the calculation results of the flaky particle model are more accurate.