Stability of Pile Groups


Yiyuan Zhao , Henryk Stolarski

January 1999

Report no. MnDOT 1999-31

Current research focuses on advancing the existing capabilities for stability analysis of pile foundations. To this end, researchers developed a continuum model and a structural model. In the continuum model, three-dimensional solid finite elements and mapped infinite elements are employed for modeling the three-dimensional geometry, pile-soil-pile interaction, and unbounded domain whereas threedimensional thin-layer interface elements are used for modeling interaction behavior between the pile and the soil. In contrast, thin-walled structural elements and flat shell elements are used for the piles and pile cap in the structural model. Nonlinear soil springs are adopted for modeling the lateral and axial pile-soil interaction. The continuum model is capable of accounting for pile-soil interaction and pile-soil-pile interaction appropriately whereas the structural model is efficient and simple to implement. To include pile-soil-pile interaction for groups of closely spaced piles, the group-reduction factor is introduced in an approximate fashion in the structural model. Both the continuum model and structural model developed in the current study are used together for some representative but simpler pile configurations to obtain the group-reduction factor.

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