Abstract:Geotechnical construction disturbs soil mass, destructs soil fabrics, reduces soil strength, and causes soil deformation, all of which can result in the deformation and destruction of adjacent buildings. According to the value of soil shear strain, the soil surrounding a construction site can be divided into:strongly disturbed zone, disturbed zone, micro-disturbed zone, and undisturbed zone. Therefore, a soil constitutive model needs to consider the small strain characteristics and disturbance characteristics of the soil. Methods for determining key parameters of a hardening soil model with small strain stiffness (HS-Small model), including initial shear modulus and threshold shear strain, have been presented and analyzed. Drained triaxial tests and oedometer tests were performed on typical soils in Shanghai, and the corresponding model parameters were determined. The in situ testing methods are recommended for determining the initial elastic modulus of soils. Sensitivity analysis of the HS-Small model parameters, including initial shear modulus and threshold shear strain, revealed that the initial slope of the compression curve and the unloading-recompression curve increased with the increase of the initial elastic modulus. With increasing threshold shear strain, both the approximate straight segments of the compression curve and the unloading-recompression curve lengthened. Under same shear stress conditions, the shear strain of the soil decreased, while the interval range of the initial elastic modulus of the soil constantly increased.
