This leads to a larger soil yielding, which itself modifies the uplift behavior of the foundation.
The Pasternak model (also referred to as the two-parameter model) was widely used to describe the mechanical behavior of the foundation, in which the well-known Winkler model is a special case.
Model tests and numerical analyses in 2D and 3D are used to investigate how the bars' position and direction affect the behavior of the foundation under different load conditions.
This was assumed because the initial studies on the behavior of the foundation system demonstrated that, for the design specifications of the foundation system and under the conditions used for this study, the foundation and pedestals did not exhibit a considerable amount of nonlinear behavior.
For this purpose, five structural models of IBs are built in decreasing levels of complexity starting from a nonlinear structural model including close numerical simulation of the behavior of the foundation and backfill soil and gradually simplifying the model to a level where the effect of backfill and foundation soil is totally excluded.
The behavior of the foundation soils are described by a cyclic elasto-plastic constitutive model in which, the stress-induced anisotropy, the density and structure of ground can be described in a unified way, while the tunnel structure is simulated using elastic solid elements and beam elements.
The behaviors of the foundation soils are described by means of a cyclic mobility constitutive model which was developed at the bases of modified Cam-clay model by introducing concepts such as stress-induced anisotropy, over-consolidation, and structure.
Nevertheless, the influence of some relevant parameters in the overall behavior of the retrofitted foundations has not yet been studied.
In the current practice, when the scour-affected behavior of the pile foundations is analyzed, either the whole scour-hole geometry or the possible changes in the stress history of the remaining soils is often ignored.
This is because of the nonlinear behavior of the soil-foundation interface.
