Experimental Study On Soft Soil By True Triaxial Test And The Constitutive Model Parameters

Affected by factors of geological structure, stress history, composition and other particles, Soft soil with obvious regional, Physical and mechanical properties of soft soil are quite distinguishing in different regions. Yingkou area with soft soil is a typical representative of the silty clay Liaoning coastal alluvial plain formed by the delta region. With subways, tunnels, and other projects in soft soil foundation pit deformation and strength issues become increasingly prominent, which need to enhance the acquaint of soft soil areas in Yingkou. So it is necessary for further systematic study of the physical and mechanical properties of soft soil area, which is provided with high referential significance in the theory and applications. Through the way of collecting engineering geological data, laboratory soil testing, theoretical analysis to start Yingkou soft soil research. Specific results are as follows:Through collecting engineering data and doing laboratory soil tests to obtain the basic physical and mechanical parameters of Yingkou area soft soil, making a comparative study with Shanghai and Tianjin soft soil. It summarizes the physical and mechanical properties of soft soil in Yingkou areas.If physical and mechanical parameters with obvious correlation, using linear regression to fit and obtaining a linear regression equation. It has practical significance and value for prediction and evaluation parameters.In order to study anisotropic deformation characteristics of soft soil, true triaxial tests are carried out by a three-way direction of principal stress load to analyses of the deformation of soil under different loading direction. Different intermediate principal stress ratio has an important influence on the specimen in the under the conditions of true triaxial test;With intermediate principal stress ratio changing, obtaining the trend of soil cohesion and internal friction angle. Soil moisture content from 15% to 25% of the maximum intensity difference rate close to 35%,Get the sample by the experimental results under different moisture content of p-q critical state line in the plane,can be a better fitting a straight line.Moreover according to the three dimensional stress state of soil mass destruction when get the n in the plane of the yield curve,its yield locus in ? plane close to SMP.The normalized method is used to quantitatively analyze true triaxial test results. Compared with several common normalization factors and obtain the stress-strain normalization equation, which can well evaluate and predict stress-strain relationship under different confining pressures. Duncan-Chang model can't consider soil anisotropy, one kind of Duncan-Chang constitutive model is proposed that it can combine with soil amendments based on the true triaxial test results. The model is applicable after true triaxial tests to verify. The results provide a practical and simple way for soft soil to simulate and analyses the three-dimensional stress state.