The Experiment Study Of Soil Medium On Scale-span Strength And Deformation Property

The soil is the product of rock, which suffer from the process of transport and depositionby weathering, gravity, flowing water and wind, and belong to intensive particles medium.Granular material is non-continuous material which is gathered together by particles ofdifferent size in a certain way. The mechanical properties of granular material, with complexand special mechanical behavior, are related to microstructure and micro-property of the size,shape, distribution and the link of the particles.Particle material especially in micro-size has the special mechanical properties of physics,such as scale effet. The classical plasticity theory didn’t contain the characteristic parameterthat is able to show the different mechanical behavior caused by different scale levels, so itcan’t predict accurately the different mechanical behavior due to different scale levels.Because of geotechnical medium with the non-continuty and properties of granular materials,scale effect of granular materials has a certain effect on physical and mechanical properties ofsoil such as strength and deformation. In this paper soil will be divided into two mediumaccording to the size of soil particles, matrix and reinforcement particles. The size of matrixparticles is less than0.075mm and the size of reinfoecement particles is larger than0.075mm.The matrix particles combining with pore water consititute aggregate, reinforcement particlesare wrapped by matrix particles, and then “matrix-reinfoecement” model is formed. Takesome experimental study on scale-span strength and deformation of soil granular material,considering the influence on physical and mechanical properties of soil medium caused bysize of reinforcement particles within a certain rang, and then get some mechanical deductionand analysis to “matrix-reinforcement” model based on MSG theory.The outlines of the study tasks and achievement of the dissertation are listed as follows:(1) Take some study on sample preparation of soil formed from “matrix-reinforcementparticles”. It is the most important to control moisture content of matrix and sample density inthe process of sample prepraration. Moisture content of matrix is relatively closer to value oftheoretical calculations by the non-saturated method, while the samples, which have to besaturated by saturation method, are difficult to achieve consistency of moisture content ineach part after the samples are saturated although moisture content of matrix is kept the samebefore saturation. The samples prepared by saturation method can’t achieve state of the idealsaturation generally and moisture content of matrix may be influenced by capability ofadsorbed water of sand particles during the process of saturation. Therefore, the samples areprepared by non-saturated method for the experiment of direct shearing and triaxial compression.(2) Take some experiment study of direct shearing on soil formed by matrix-reinforcementparticles. The yield strength of soil is improved after reinforcement particles are added tomatrix particles. The sand percentages and the specific surface area of reinforcement particlesare two major factors that have an effect on yield strength and shearing strength of soil. Theyield strength and shearing strength of soil increases with the increasing sand percentages.(3) Take some unconsolidated undrained test on soil of “matrix-reinforcemengt particels”.The yield strength and yield strain of soil basiclly increases with increasing specific surfacearea of combination of reinforcement particles. The reinforcement particles have an influenceup on strength and deformation of soil due to the size effect. The liquidity index of martrixmaterial is one of the major factor that may influence the strength and deformation of soil.The higrer the liquidity index of matrix is, the lower the strength of soil may be.(4) Take some consolidated undrained test on soil of “matrix-reinforcemengt particels”.The amount of sand is an important facror that can influence the strength of soil directly andthe yield strength of soil increases with increasing amount of sand. For the same sandpercentages the smaller the specific surface area of reinforcement particles is, the greater thestrength of soil may be, existing certain size effect. The confining pressure of experiment andthe liquidity index of matrix are two main factors that can influence the strength anddeformation of soil. After unconsolidated undrained test or consolidated undrained test thesamples formed by “matrix-reinforcement particles” appear to be tympanous shape.(5) Make some mechanical derivation for theoretical model of “matrix-reinforcementparticles” basced on MSG theory and analyse the mechanism of scale-span strength anddeformation of soil medium. The concept of the inside scale of soil is established and set up acertain relationship between macroscopic parameters and microcosmic parameters of soil.