THREE-DIMENSIONAL NONLINEAR SOIL-STRUCTURE INTERACTION ANALYSIS OF PILE GROUPS AND ANCHORS.
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PublisherThe University of Arizona.
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AbstractAnalysis and design of structures supported by geological media pose various complexities such as nonlinear behavior of supporting media, nature of loading, irregularities in geometry and boundary condition, and the interaction effects. It is extremely difficult to find closed-form solutions for such problems. So often, numerical techniques such as finite difference, finite element and boundary integral methods are used. In this research two soil-structure interaction problems are analyzed using the finite element method involving fully three-dimensional idealizations. In order to incorporate nonlinear behavior of a soil, a nonlinear elastic (hyperbolic model), and generalized single surface plasticity model including hardening are implemented in the finite element program for analysis of a pile group foundation, and an anchor in sands, respectively. The parameters required to define these models are determined from comprehensive laboratory stress-strain data obtained by using a multiaxial testing device. Typical stress paths are back predicted using the generalized plasticity model to verify that it is capable of predicting those paths, and is found to be satisfactory. In order to include the interaction effects resulting in relative slip and debonding or crack and openings at the junction between two dissimilar materials, the thin-layer element model is implemented. Load deformation behavior, force and stress distributions in various components of pile group foundation, and the anchor-soil system are predicted by using the numerical procedure. The predictions are compared with results from a model test for the pile group and field observations for the anchor problem; the comparisons are found to be satisfactory. The effects of soil nonlinearity and interface behavior are also delineated and it is found that their inclusion, particularly in case of anchors analysis, can substantially effect the behavior of the system. Detailed analysis of the results permits an increased understanding of the stress deformation mechanisms of the three-dimensional problems.
Degree ProgramEngineering and Engineering Mechanics