Bounding Surface Cam-Clay Model with Cohesion for Cement-Admixed Clay

Abstract

This paper proposes a constitutive model for cement-admixed soil based on the concept that the effect of cementitious bonding can be accounted for by incorporating a cohesion term into the Cam-clay flow rule. The cohesion is not a constant; instead, it is allowed to decrease during loading to simulate the loss of bonding. The loss of bonding during loading is assumed to be related to the plastic work done against the structure. In other words, yielding and postyield behavior are mechanistically rather than phenomenologically based. This allows the shape of the yield surface to evolve from a nonelliptical shape to an elliptical shape as cohesion is lost during loading. Comparison with experimental results of undrained triaxial shearing tests over a range of mix proportions and confining pressures shows that the behavior of undrained specimens is well represented. Comparison with experimental results of drained triaxial shearing tests shows that the behavior of drained specimens is well represented up to the peak strength. The gradual yielding up to the defined initial yield point can also be captured by introducing a bounding surface.