Investigation of bridge abutment displacements constructed on piles and geogrid reinforced soil using the finite-element method

One of the major problems of highway and railway bridges is the settlement of the bridge abutments, whose reduction has always been set as the research target. Two methods that have been widely used for controlling the settlement are either reinforcing the abutment subsoil with geogrid or constructing the abutments on piles. This paper describes the application of a two-dimensional Finite-Element Method (FEM) by using Plaxis 2D V8.5 for comparing the performances of these two methods. The effect of the geogrid normal stiffness, length, and depth of reinforcement on the horizontal and vertical displacements of abutment is also investigated. Data from an instrumented bridge abutment have been used for the model verification. The reduction of the bridge abutment, the vertical settlement, and the horizontal displacement by pile and geogrid have been analysed and compared. It is found that constructing the abutment on piles has a better performance in reducing the vertical settlement of the bridge abutment. However, lower lateral displacement can be obtained by using a geogrid with higher normal stiffness. It is also found that while the vertical settlement is not affected by the geogrid stiffness, the horizontal displacement of the abutment decreases by increasing the stiffness.