A Critical State Constitutive Model for Overconsolidated Soils in Transportation Infrastructure Construction

The extensive construction of infrastructure such as high-speed railways and expressways has made significant contributions to socio-economic development. However, this development necessitates more precise calculations and predictions regarding embankment deformation. Embankment soils often exhibit overconsolidation, leading to dilatancy and softening behaviors. In order to capture the inherent complex behaviors of overconsolidated soil with a concise constitutive model, a critical state model is constructed based on the concept of hyperbolic equation. In recognition of the inherent limitations within the Duncan–Chang hyperbolic model, a modified hyperbolic equation is introduced here. This modified equation captures the softening behavior of the soil after reaching peak strength by simply transforming the original equation. Based on the framework of critical state theory, an incremental constitutive model is constructed by integrating the modified hyperbolic equation. With this attempt, the model addresses two major limitations of the Duncan–Chang model: dilatancy and softening behavior. Subsequently, the triaxial formula is extended into the multi-axial stress space. The simulation ability of the model is demonstrated by comparing the model responses of four different soils with the actual data. In both drained and undrained tests, the model can simulate the mechanical responses of soils with different overconsolidated degrees with great precision.