Experimental And Theoretical Analysis Of The Influence Of The Characteristics And Shape Of Soil Particles On The Settlement Of Particles

The particle analysis test is one of the most important test items in the geotechnical test.For the particle size composition of soil with a particle size of less than 0.075 mm,the settlement analysis method based on the Stokes formula and laser scattering method is commonly used in practical engineering.The mineral types of soil particles are different,and their particle shapes and surface physical and chemical properties are different.Whether the mineral particles are ideal spheres,whether they have unsaturated charges,and other physical and chemical characteristics will directly affect the sedimentation rate of the particles,and then affect the sedimentation analysis method based on the Stokes formula to test the particle size distribution.According to the characteristics of light absorption and scattering angles of different particles in the suspension,the laser scattering method collects and analyzes the scattered light intensity information to invert the particle size composition.The test results have nothing to do with the sedimentation rate of the soil particles.Therefore,based on previous studies,this article uses commercially available high-purity clay minerals with different particle sizes in the shape of flakes,such as kaolin and montmorillonite,and non-clay minerals with spherical(granular or massive)particle shapes,such as quartz and feldspar,a series of artificial soil test samples with different flake particle content and different particle sizes are configured to perform conventional particle analysis tests and laser scattering particle analysis tests to compare and analyze the influence of the different mineral properties of different mineral types on the results of the particle analysis test of the sedimentation analysis method,and to further reveal the sedimentation laws and dynamic characteristics of the sedimentation of particles of different shapes through experiments and numerical simulations.The main research work and achievements of this paper are as follows:(1)Four high-purity artificial minerals particles(quartz,feldspar,kaolinite,and montmorillonite)are prepared as a single mineral or configured in a certain proportion,and laser scattering method and sedimentation analysis are used to test different mineral samples with the same mesh and mineral mixed samples with the same mesh and compare the test results.The test results show that the test results of the sedimentation analysis method are affected by the mineral properties,clay minerals have a greater influence on the settlement analysis method,while non-clay minerals have a smaller influence on the settlement analysis method.The unevenness of the soil sample gradation measured by the settlement analysis method is higher than the actual situation.The larger the proportion of clay minerals,the more uneven the result measured by the settlement analysis method.(2)The laser particle size analyzer calculates the particle size according to Gustav.Mie scattering theory.Based on this principle,it can perform laser testing at different moments of particle settling,and analyze the changes in particle movement according to the calculated particle size changes.Therefore,experiments can be designed to study and analyze the sedimentation characteristics of mineral particles of different shapes represented by the four mineral particles of quartz,feldspar,montmorillonite,and kaolinite.The test results show that when the flake-shaped clay mineral particles begin to settle at a certain initial inclination angle,they will finally settle in a stable state where the plane is parallel to the sinking speed,that is,the flake-shaped particles will deflect to a stable settlement state as they settle;(3)Using numerical simulation methods,with spherical particles and flaky particles as representatives,the sedimentation process of mineral particles of different shapes is simulated and calculated.The results show that as the orientation angle of the flaky particles gradually increases from 0° to 90°,the maximum sedimentation rate when the flaky particles reach a stable sedimentation state gradually decreases;Under the same volume,spherical particles settle faster than flake particles;When the flake particles settle at a certain orientation angle,the asymmetric flow resistance will form a certain resultant moment by the center of mass of the flake particles.When the orientation angle of the particles is 45°,the absolute value of the resultant moment is the largest.