Based on a series of physical property tests and static triaxial tests of marine soft soil near shore in Zhejiang Province, China, the hyperbolic relationship is gained between the mean stress and the generalized shear stress value. Then the modified Rhodes stress angle is considered in the model. The Cambridge model is modified and make it more responsive to the static characteristics of marine soft soil. The UMAT material constitutive subroutine of finite element software Abaqus is compiled, and a modified Cambridge model of marine soft soil is developed. The static triaxial simulation test is carried out by Abaqus, and the rationality of the improved model is verified. The results show that the modified Cambridge model of marine soft soil effectively simulates the stress-strain characteristics of marine soft soil, the nonlinear characteristics of the soft soil and the characteristics of the plastic flow.
As one of the stress-strain models describing incremental theory of plasticity (Roscoe, Schofield and Thurairajah, 1963), the Cambridge model (Roscoe, Schofield and Wroth, 1958; Roscoe, Barland, 1968; Zienkiewicz, Taylor and Zhu, 2013) is widely used in soil mechanics. Due to the differential soil properties, this model is modified in various specific applications, based on which, the cambridge model of marine soft soil should be modified on its shortcomings and the particular characteristics of marine soft soil. Y Chen (2002) considered the rheology of soil, based on the modified Cambridge model present a new modified Cambridge visco elastic plasticity model. YH Guo (2015) improved Cambridge model and got the accuracy of the elastic-plastic matrix improvement model, by using the Cambridge model to calculate the volumetric strain and shear strain of soil theoretically. There are also some researchers have improved the Modified Cam-Clay Model to make it compatible for overconsolidated soils (Amerasinghe, Kraft, 1983; Xu, Qi and Gao, 2008).
In this paper, based on the physical mechanics experiments, by fitting the mean stress and the generalized shear stress value, the state line of marine soft soil is hyperbolic, and the modified Rhodes stress angle are considered in the model, the further improvement of the Cambridge model and make it more responsive to the static characteristics of marine soft soil, which is validated by the secondary development of UMAT material constitutive subroutine in Abaqus.
