Numerical analysis of stress concentration around bridge bank seat in Geosynthetic Reinforced Soil – Integrated Bridge Systems (GRS-IBS)

Geosynthetic Reinforced Soil – Integrated Bridge Systems involve directly supporting the bridge abutment bank seat on the top of a reinforced soil structure without piles or bridge bearings. Analysis, using Plaxis 2D, found that the arrangement of geogrid in the upper part of the reinforced soil abutment, the distance of the abutment bank seat from the wall face and the direction of horizontal load application were important considerations in controlling the deformational response of the abutment. Placing the bank seat further away from the wall face reduced wall displacement, peak vertical stress and settlement under the bank seat and peak strain in the geogrid. Adding secondary reinforcement in the top of the wall reduced wall deformations, peak vertical stress and settlement under the bank seat. The secondary reinforcement redistributed the tension in the geogrid immediately under the bank seat. Longer secondary reinforcement was more efficient at controlling displacement, while shorter secondary reinforcement reduced the peak vertical stress under the bank seat. The line of maximum tension, which was largely independent of horizontal load direction, originated close to the bottom-rear corner of the bank seat and was log spiral in shape, terminating at the toe of the wall.