Abstract: Consolidated and undrained triaxial shear tests of silty clay in a section of the Poyu Bridge Project were performed by using the GDS triaxial instrument. The pore water pressure change curve and the deviator stress of the sample under different confining pressures were obtained. The deviator stress-strain curve, effective stress path and the variation curve of the pore water pressure of the sample are analyzed. The Duncan-Chang hyperbolic model is used to fit the deviatoric stress-strain relationship of the sample, and the five parameters of the Duncan-Chang hyperbolic model are obtained. The effective stress path and failure behavior of the system are summarized and analyzed. The test shows that the Poyang Lake silty clay has obvious shear expansion, and the confining pressure has a significant influence on the shear expansion of the soil; the deviator stress-strain curve of the soil is strain hardening, and the parameters of the Duncan-Chang model: k=34.74, n=0.94, R_f=0.61, φ′=30.8°, c′=13.5 kPa; the limit state stress ratio of the sample is M_c=1.32, and the effective stress path is S-shaped; the failure mode is generally drum-shaped deformation at the upper or lower part.

Key words: Silty Clay, Triaxial Test, Deviator Stress-Strain Curve, Duncan-Chang Hyperbolic Model, Effective Index, Effective Stress Path