Study of the test of saturated soft soil under axial cycling loading and unloading and the constitutive equation

An this paper, study of the test of staturated soft soil under axial cycling loading and unloading using the continuous load one-dimensional K₀ consolidation apparatus which is improved in Chang´an university. The test showed that the levels of unloading stress-strain curve is hyperbolic, the reloading stress-strain curve is hyperbolic before the load achieve at the next higher unloading level, stress strain curve is linear when to exceed, and showing constantly hardening. The sample have plastic deformation and elastic deformation. Established the constitutive equation of the axial cycling loading and unloading which based on the original hyperbolic constitutive relation, then make use of the loading curve axial maximum stress and initial tangent modulus, and make use of the unloading curve axial maximum strain and initial secant modulus, introduce new model parameters, and verified the reliability.