Study On Pore Distribution Characteristics And Permeability Of Sand Soil Based On Fractal Theory

Soil is a kind of complex structure of the porous materials.It is a kind of important resources to the survival of humans.The permeability of soil can influence the stability of the groundwater seepage,building foundation,agricultural irrigation and so on.The research of permeability pore structure plays an important influence.Quantitative description of soil pore distribution on the permeability of soil has important significance.A large number of studies have shown that the distribution of pores has fractal characteristics.At present,fractal theory is widely used to describe objects with multi-scale characteristics,but this method also has many shortcomings.For example,the physical meaning of the fractal dimension value is unclear in many cases.The fractal dimension value of the fractal model established by different scholars from different perspectives is easily confused,etc.For complex soil pore structure,when establishing the fractal model to describe its multi-scale characteristics.A single fractal dimension value cannot well fit the overall fractal characteristics.The fractal dimension of pores in different pore sizes is segmented.Based on the two kinds of unified fractal models of rock mass proposed by predecessors and combined with the seepage theory of porous media.This paper respectively deduced and established the pore distribution model and permeability model of rock mass.Meanwhile,a large number of data in literature were collected for comparative verification of the models,as follows:(1)Two types of pore distribution models are established.There are two kinds of unified fractal models of rock and soil mass summarized by predecessors.The first type takes soil particles as the research object and the second type takes pores as the research object.On the basis of these two types of fractal models and in combination with Sierpinski fractal carpet model.Two types of pore distribution models are established.(2)Two permeability models are established.Based on the two kinds of pore distribution models and the seepage theory of porous media.The permeability calculation models with fractal characteristics are established respectively.(3)A large number of soil sample data in literature were collected,two types of pore distribution models were respectively used to draw two types of pore distribution curves.The differences between the two types of pore distribution models were compared and analyzed.Then the permeability of the two types of pore distribution models was calculated with the permeability model.The permeability calculated by the two models is compared and analyzed.The difference between the results calculated by the two methods is compared.The fractal models derived in this paper provide an effective method for establishing pore distribution structure.Lay a theoretical foundation for studying permeability mechanism and enriching the application of fractal theory in multi-scale properties of soil.