Speaker
Description
Geosynthetics have become commonplace construction materials. The diverse properties of these materials enable them to fulfil a variety of functions. 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 and reinforce the base course material. The geogrid restricts the movement of grains, minimising deformation while saving material.
Triaxial tests were conducted to investigate the system behaviour of geogrids and 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 x h = 100 x 200 mm were examined. Therefore, it was necessary to scale geometrically both the base course material and the geogrid. The experimental study consisted of tests performed under monotonic and cyclic axial loading conditions. The objective of the cyclic triaxial tests was to simulate the service loads occurring in unbound base courses of railway tracks.
Due to the geometric scaling of the materials, the resulting effects had to be examined. For this purpose, large triaxial tests were performed on test specimens with dimensions d x h = 350 x 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 each of the monotonic and cyclic tests. Both, unreinforced and reinforced test specimens were investigated.
The positive effect of the geogrid reinforcement in the base course material was demonstrated in both scales. In the monotonic triaxial tests, the geogrid reinforcement demonstrated an increase in the stress that can be transferred at the equal deformation. In the cyclic triaxial tests, it was shown that the accumulated strain decreases for the geogrid reinforcement. The effects of the different specimen sizes were evaluated.