Based on the Sierpinski carpet and Menger sponge models, two categories of fractal models of rock and soil which are composed of the volume fractal model of pores, the volume fractal model of grains, pore-size or particle-size distribution fractal models are established and their relations are clarified in this paper. Through comparison and analysis, it is found that previous models can be unified by the two categories of fractal models, so the unified fractal models are formed. Experimental results presented by Katz indicate that the first category of fractal models can be used to express the fractal behavior of sandstone. A scanning electron microscope (SEM) will be used to study the microstructure of soft clay and it will be testified that the fractal behavior of soft clay suits the second category of fractal models.
This paper introduces a new means to predict consolidation deformation of soil from its microstructure.Based on a kind of pore-size distribution density function,a fractal model for soil consolidation is established.Through this model,the relation between macroscopic deformation and microcosmic pore property of soil is founded.In order to justify this proposed model for soil consolidation,consolidation experiments of soft clay are performed.Afterward,the microstructure of soft clay unconsolidated and consolidated under every pressure is studied by a scanning electron microscope (SEM).The results show that the proposed model for soil consolidation is valid in predicting consolidation deformation.
Previous porosity models have been shown to be unable to accurately describe the pore-size distribution of rocks and soils.Three new porosity models are developed in this study.Pore-size distributions of soft clay and ecotypic revetment material were obtained using a scanning electron microscope(SEM)in two-dimensional space,and with the mercury intrusion method in three-dimensional space.The results show that the new porosity models are valid in predicting the accumulative porosity of rock and soil samples.Based on the new porosity models,a new microstructure soil consolidation model was developed and the error of the compression strain prediction was less than 0.007 under low pressure.Several models for soil water retention curve were founded,which in form comprise previous models developed by other researchers,and they may be more accurate than previous models because of the valid mean for determining the fractal dimension.In addition,we obtain an expression for the relationship between soil cohesion and the test specimen size,as well as between the bulk density of rocks and soils and the test specimen size.
