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Abstract: Many interpretations of small-strain experiments indicate a non-linear dependence of soil stiffness on pressure. This shows that small-strain stiffness can be expressed as a power function of the mean effective stress rather than as a linear function of stress. Many cases in the field show the importance of these behaviours to load–deformation prediction in a soil-structure interaction problem. This paper presents a numerical implementation and validation of non-linear pressure-dependent stiffness in a hyperplasticity model using a strain-driven forward-Euler integration scheme. The kinematic hardening function was incorporated into a finite number of multiple-yield surfaces of Modified Cam Clay to characterise small-strain stiffness and accommodate smooth transition of stiffness corresponding to different loading conditions and stress histories. Experimental results of current state and loading history dependence in overconsolidated clay are compared to the model prediction. [Copyright &y& Elsevier]

A continuous hyperplasticity model named kinematic hardening modified cam clay (KHMCC) is a constitutive soil model based on thermodynamic principles. This model has addressed some shortcomings of the modified cam clay (MCC), specifically on small strain stiffness. Because of employing multiple surfaces plasticity, it can simulate a smooth transition from elastic to plastic behaviour as well as the effect of immediate past stress. This article aims to present some important issues on the numerical implementation of the continuous hyperplasticity non-linear KHMCC model. The incremental stress-strain response is calculated based on a rate-dependent algorithm. A significant advantage of the rate-dependent calculation is that it is not necessary to attach with the consistency condition during calculation of plastic strains. Effect of time step and number of yield surfaces in rate-dependent algorithm will be also presented. A discussion on using of numerical integration rules of hardening functions is addressed. Furthermore, model verification is performed against analytical solution of ideal undrained response which has been obtained from theoretical integration of the MCC function over the imposed stress or strain path. Finally, some numerical demonstrations are also carried out to illustrate several key features of the model. [ABSTRACT FROM AUTHOR]