The interaction behaviour of geogrid reinforced soil is significantly influenced by the direction of force transmission between geogrid and soil. If a geogrid is pulled out, the soil is directly activated by the applied geogrid displacement, which is at least greater than the displacement of the surrounding soil. As a result, the tensile force in the geogrid is transferred by friction and earth resistances into the soil. In contrast to that, geogrids in base layers or foundation pads are indirectly activated by an applied load via the surrounding soil. In particular, this type of geogrid activation involves a fundamental need for research with regard to forces and deformations. This paper gives an overview of the existing concepts of interaction and classifies them into a global and a local approach, distinguishing between direct and indirect geogrid activation. Furthermore, a test stand for the investigation of the local interaction mechanisms during indirect geogrid activation is presented. For this purpose, transparent geogrid reinforced specimens are biaxially loaded, whereby an area-wide and undisturbed insight into the geogrid-soil interface is enabled. The transparent soil is created as a two-phase medium consisting of crushed quartz glass and a white oil with a corresponding refractive index. First experimental results show the displacement fields of geogrid and surrounding transparent soil, whereby the "pushout" and "interlocking" mechanisms can be identified. At the edges of the load area, the soil is pushed over the geogrid, whereby the spreading forces are transferred into the geogrid (“pushout” mechanism). In contrast to that, there is no relative movement between the soil and the geogrid in the core area of the load, but the soil grains interlock with the geogrid openings ("interlocking" mechanism). In particular, the interaction mechanisms in the transition area need to be further explored. The present investigations serve as a basis for soil-mechanical approaches in order to describe the interaction mechanisms and to create an interaction model for the case of indirect geogrid activation.