Limitation of Geosynthetics Usage on Road Subgrade

There are several ways of geosynthetics functionality. Well-known mechanisms are functions of separating, filtrating, protecting and slope reinforcing. There are several publications describing the influence of geosynthetics on increasing the soft-soil bearing capacity and their positive role on final subbase deformation. However, this geosynthetics functionality has not been explained satisfactorily in detail yet. The research presented here deals with clarifying the possible geosynthetics functionality. Six kinds of geosynthetics of world renowned producers were selected for testing. The measurement was carried out in the Geotechnical Laboratory Testing Field (GLTF), which is a facility constructed for fullscale geotechnical measurements. The results of static plate tests show that the contribution of the geosynthetics to the bearing capacity increase is very limited. A significant increase appears only in the case of a very low bearing capacity subgrade covered by a 20 cm thick subbase layer reinforced by some geosynthetics. After the static part of the experiment the GLTF was equipped with a cyclic loader to simulate real traffic loading and tests for the evaluation of possible bearing capacity increase and deformation decrease due to geosynthetics usage were repeated.