The effect of the geometrical properties of geocell reinforcements between a two-layered road structure under overload conditions

Abstract

Depending on the project traffic, the total thickness of a granular base can reach excessive values. Granular layers of large thicknesses undoubtedly extend the duration of a project and cause high project total costs. In this study, the improvement in settlement behaviour of unbound granular base layers reinforced with geocell was investigated by way of large-scale laboratory tests and finite element modeling. Plate loading tests were performed on unreinforced and geocell reinforced base layers, which were constructed on subgrade soil with a low bearing capacity under 1750 kPa overload condition. It was determined that the amount of settlement observed at the same stress levels decreased with an increase in the aperture size from 440 mm to 660 mm and the geocell height from 100 mm to 150 mm. The reduction in settlement potential, which reached 78% compared to the unreinforced reference section around 25 kPa, decreased to 55% at around a 200 kPa standard load. With an increase in the vertical stress level, the effectiveness of geocell reinforcement decreases and a serious decrease occurs after 500 kPa, becoming completely unserviceable when a level of 1000 kPa is to be exceeded. Although the difference between the experimental results and the modeling values remained below 5% in the reference section, it reached as high as 30% differences in the geocell implemented sections up to 200 kPa, due to three-dimensional geocell adaptation problems within the finite element calculations. In this way, it will be possible to increase the performance of road surfaces by keeping the pavement thickness constant, and also it will be possible to design more economical sections by reducing the required thickness.