|Institution:||Louisiana State University|
|Department:||Civil & Environmental Engineering|
|Keywords:||three dimensional; finite elements; retaining walls; soldier beams; earth pressure|
|Full text PDF:||http://etd.lsu.edu/docs/available/etd-04092007-161907/|
The objective of this study was to perform an engineering assessment of key three-dimensional (3-D) soil-structure interaction (SSI) features of selected earth retaining walls utilizing the nonlinear finite element method (FEM). These 3-D features are not explicitly incorporated in conventional two-dimensional (2-D) procedures that are commonly used to design these retaining walls. The research objective was accomplished utilizing the nonlinear FEM. The retaining walls selected for this research were described in detail. Design methodologies and computed responses for the walls based on conventional 2-D design procedures were summarized. Key engineering features of these structures such as construction sequence and system loading were identified. Three-dimensional responses relating to these wall systems that are not explicitly included in current 2-D methodologies were described. An engineering assessment of key 3-D SSI responses of the retaining wall systems utilizing 3-D FEM analyses was performed. Results from the 3-D nonlinear (FEM) analyses were used to determine the state of stress in the soil adjacent to the structure, which indicates the amount of shear strength in the soil that has been mobilized. Three-dimensional nonlinear FEM analyses were used to compute deformations of the structure and the surrounding soil resulting from SSI behavior. Deformations resulting from the interaction between the structure and the soil are not explicitly included in simplified 2-D design procedures. Results of the comprehensive 3-D analyses were compared with full-scale field test results for the walls as a means to validate the FEM models. The 3-D responses of the wall systems were summarized to quantify their impact on the overall behavior of the retaining walls. Finally, an assessment of simplified 2-D procedures was performed for the selected retaining walls, based on insight gained and critical factors identified by the comprehensive 3-D analyses. It is envisioned that the behavior of these specific retaining walls can be further understood and the critical features can be identified by the comprehensive 3-D analyses. It is also envisioned that the 3-D nonlinear FEM approach can provide useful information to help validate or possibly enhance simplified 2-D limit equilibrium and simplified computer-aided procedures used to analyze these walls.