Short Term Nonlinear Finite Element Analysis of Settlement Control for Bridges Approach Slab Using Geogrid Technique

Abstract

It is always recommended to improve the properties of the soil beneath the bridge approach slab to increase its ability in bearing different applied loads and to control the expected generated settlements. The most methods used to improve the soil are in using a compacted soil with or without reinforced by a single geogrid layer or multi- geogrid layers at different spacing (depths).  This study presents a three-dimensional, short term nonlinear finite element analysis of settlement control for bridges approach slab using the geogrid technique by using (ANSYS v.15.0) software. The finite element models adopted in this study have two parameters; number of geogrid layers (one, two, three and four layers)and soil type (compacted soil and soft soil). While the approaches slab thickness, slab reinforcement, concrete compressive strength and load type (equivalent lane loading of AASHTO HS-20) and load position are kept constant.Analysis results show that the vertical displacement (settlement) under the applied load (asphalt paving) decreases with the increase of soil modulus of elasticity.  Also, the presence of one, two, three and four geogrid layers lead to decrease of vertical settlement to (53%), (65%), (67%) and (71%) respectively. Also, the first layer (which placed directly below the asphalt paving) exhibits more efficient to decrease vertical settlement than the other layers.