Finite element modeling of reinforced earth embankments
Description
This dissertation describes the development of a finite element program for the analysis of conventional and reinforced embankments. The results of the program are verified with the field measurements of three full scale test sections constructed on soft soils. A parametric study is performed to investigate the effect of various components of a reinforced embankment on its behavior A finite element program was modified to include new finite elements and material models for soil, reinforcement, and interface. The program is now capable of modeling embankments under undrained, drained, and consolidation conditions. A creep inclusive elasto-plastic stress-strain model is used to represent the plastic behavior of soils and a hyperbolic stress-strain model is used to model the behavior of soils under nonlinear elastic conditions. The interface between the soil and the reinforcement is modeled by isoparametric joint elements with no thickness. The stress-strain model of the interface is also based on a hyperbolic stress-strain model. The reinforcement is modeled by isoparametric bar elements capable of transmitting axial forces through a linear stress-strain relationship The results of the finite element analyses agree with the field measurements of horizontal displacement, vertical displacement, forces, and pore pressure. The results of the parametric study indicate that the reinforcement strength has a major influence on reducing horizontal displacement, whereas the effect of the shear stiffness and the interface condition is relatively modest. The increase in the soil stiffness reduces the horizontal displacement significantly in both the foundation soil and the embankment. Accurate estimation of the coefficients of permeability is essential for predicting the horizontal displacement in the foundation soil and the tensile force in the reinforcement even for short term analysis. The bottom boundary of a finite element mesh of an earth embankment should be placed at a depth of twice the height of the embankment, whereas the lateral boundaries of the mesh should be at a distance of twice the depth of the foundation soil to eliminate the effect of the boundary conditions on the results of the analysis