Large scale testing of reinforced unbound railway base courses

Abstract

In the disciplines of geotechnical engineering and transport infrastructure construction, geogrids are utilised to improve soil behaviour and carry tensile forces. In the context of unbound base courses, geogrids are most frequently implemented to stabilise the material. They restrict the movement of grains and minimise deformation while saving material. Triaxial tests were conducted to investigate the system behaviour of geogrids within unbound base courses. In order to reduce the amount of work and material consumption, as well as to use a standard triaxial device, samples with dimensions of d · h = 100 · 200 mm were examined with geometrically scaled materials. The experimental study consisted of tests performed under cyclic axial loading conditions. Due to the geometric scaling of the materials, the resulting scaling effects had to be examined. For this purpose, large triaxial tests were performed on test specimens with dimensions d · h = 350 · 700 mm. With this specimen size, commercially available geogrids and a 0/45 base course material could be used. In order to investigate the scaling effects, one stress level was examined in the cyclic tests. The positive effect of the geogrid reinforcement in the base course material was demonstrated in both scales. It was shown that the accumulated strain decreases in case of the geogrid reinforcement.