Full-scale field tests on geosynthetic reinforced unpaved roads on soft subgrade

A full-scale field test on a geosynthetic reinforced unpaved road was carried out, including compaction and trafficking, to investigate the bearing capacity and its performance on a soft subgrade. The test track was built with three layers of crushed, recycled fill material. The 1st layer was compacted statically, whereas the 2nd and 3rd were dynamically compacted. The geogrids were instrumented with strain gauges to measure the short- and long-term deformations and the ongoing formation of ruts was assessed from profile measurements. The various geosynthetics used for this reinforced unpaved road were found to have a relevant reinforcing effect only when used under a thin aggregate layer on a soft subgrade. Under such conditions, ruts can form in the subgrade, mobilizing strains and thus tensile forces in the geosynthetic. The achievable degree of reinforcement depends on the stiffness of the geosynthetic and is limited by finite lateral anchoring forces.