Abstract:
Multi-dimensional (2-D and 3-D) soil creep models are generalized from Bjerrum's I-D creep
model (Bjerrum, 1967), which is based on field test data. This model is based on an expression
for creep strain rate, and was later modified for transient loading conditions. In the present
work, this differential form of I-D creep model is extended to multi-dimensional (2-D and 3-D)
state of stress and strain by incorporating concepts of visco-plasticity. The devised 2-D and 3-D
creep models take into account both volumetric creep strain and deviatoric creep strain, and
creep deformation of the soil is defined by several material parameters. A non-linear, time
incrementing finite element program, along with iterative corrections within each time step, had
been developed by the second author (Puswewala et al. 1992). Certain modifications were done
in the latter main program to incorporate the present model as an element subroutine for plane
strain condition. The numerical model will enable to check the sensitivity of model parameters
on predicted results as well as the time-dependent solution of complicated foundation-soil
interaction problems involving creep of soil. Numerical analyses are conducted using published
experimental data and parametric studies are conducted to evaluate the sensitivity of different
input parameters of the model. The verified program will be an important resource tool for
estimating settlements in structures founded on soils exhibiting creep.
