The Experimental Research And Macro And Microscopic Mechanism Analysis Of Soft Soil Strength And Deformation Characteristics

Soft soil is a kind of heterogeneous material composed of solid, liquid and gas phase, with the high water content, macropore, low intensity and permeability, high compression, structural and rheological characteristics. At present, the researches about soft soil's intensity and deformation focus on the macro level, while the macroscopic studies cannot reflect the micro nature of that, thus it has an important significance to study physical factors and mechanism of soft soil's intensity and deformation in microscopic perspectives.The paper makes experimental study and the mechanism analysis about the influence of soft soil's intensity and information on its mineral composition, pore solution concentration and the initial water content and other factors from the microscopic view.This article contains the following aspects:1. Meso parameters test of soft soil. Through a series of physical and chemical tests, measure actually the sample specific surface area, cation exchange capacity and convert surface potential by using surface charge density.2. Experimental research about soft soil strength properties. Do the direct shear experiments for different soil samples on composition, pore liquid thickness and water content, then find the variation rules by which shear strength and indexes change with each parameter above mentioned.3. Experimental study on soft soil's plastic property. Do plastic property experiment on soil samples with different composition and pole liquid density, and analyze the variation rules by which the plasticity index change with each parameter above-mentioned.4. Experimental study about consolidation deformation of soft soil. Do consolidation deformation experiment on samples with different compositions, and analyze the influences which composition proportion, pore liquid ion concentration, and water content have on soft soil's consolidation deformation. Determine the relationship between micro parameter and coefficient of consolidation.5. Experimental study about rheological properties. Through a series of rheological tests, analyze the influences which composition ratio, pore solution ion concentration, water content make on the rheological properties, and explain the rheology producing mechanism by using the four-phase model of soft soil.The main research findings:1. Mineral composition, crystal structure types have significant influence on soil specific surface area, cation exchange capacity, surface potential and other microscopic parameters.2. The main factor affect the plastic properties of soil in the final analysis are as combined water film thickness of fourth material composition of soil.3. It can be found that, through the experiment about strength characteristics, when the total amount of bentonite gets to 1 / 3, the whole soil shows the nature of clay, and pore fluid ion concentration has greater influence on strength of soil with more clay minerals than that with less clay minerals.4. The result of consolidation test results showed that soils with different mineral composition have different internal drainage performance ; other pore solution concentration has different influence on consolidation with different mineral compositions.5. Through a series of rheological properties tests, it can be found that in general clay minerals increase, pore solution concentration decreases, the soil will reduce the flow resistance, flow phenomenon is more remarkable; the initial soil water content affect the rheological properties of soil, moisture content in the plastic limit flow occurs near the critical point of the most significant.6. Fitting results of log function empirical formula and the model formula of four components Burgers show that both can simulate rheological properties of the soil body at a certain degree.Through series of macro and micro experimental study and mechanism analysis on strength and deformation characteristics in this article, understand the micro-mechanism of microscopic parameters impacting soft soil's shear strength, consolidation, plastic and rheological properties and others, which can provide valuable reference work for soft ground, side scope engineering and building design and construction.