There are several ways of the 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. 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 gesynthetics of world known producers were selected for the measurement. The measurement was carried out in the Geotechnical Laboratory Testing Field (GLTF), which is a facility constructed for full-scale 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 case of a very low bearing capacity subgrade covered by a 20cm 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 due to geosynthetics usage were repeated.