Modified Hyperbolic Model Considering Strain Softening Characteristics of Fine Sand
During the process of foundation construction,the foundation made of fine sand may experience liquefaction under the action of overlying loads.In order to explore the strain softening characteristics of saturated fine sand,unconsolidated undrained triaxial shear tests on Hefei fine sand are conducted using an automatic environmental triaxial testing system.The strain softening characteristics of fine sand under different confining pressures are analysed and its softening mechanism is revealed.The research results indicate that the unconsolidated undrained shear stress-strain curve of Hefei fine sand exhibits a significant peak-type softening characteristic.Confining pressure has a significant influence on its stress-strain curve,with the peak deviator stress and corresponding peak strain positively correlated with the consolidation confining pressure.The relationship between peak deviator stress and consolidation confining pressure can be expressed by a linear function(σ1-σ3)p=0.637σ3+255.5,with a fitting determination coefficient R2 reaching 0.983.The relationship between peak strain and consolidation confining pressure can be expressed by a linear function εp=0.0031σ3+5.45,with a fitting determination coefficient R2 reaching 0.982.During the shear process,the fine sand specimen exhibits shear dilation,leading to gradual destruction of the soil structure and subsequent strain softening.By adding new boundary conditions to the hyperbolic formula proposed by Academician Shen Zhujiang to simplify the model parameters,a modified hyperbolic mathematical model for strain softening of Hefei fine sand is constructed.This model fits well with the stress-strain softening curve of Hefei fine sand and provides important basis for the design and construction of underground engineering in Anhui Province.
fine sandtriaxial teststrain softeningnonlinear mechanical modelstress-strain curve
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