Abstract:
The safe operation of tracked vehicles on temporary working platforms built over soft, cohesive soils poses significant geotechnical challenges. Although the use of geogrid reinforcements has established themselves as a method for improving bearing capacity and reducing differential settlements providing economic and ecological benefits, their design is still largely empirical. This study presents the results of a large-scale field trial to validate the performance of a laid and welded geogrid used as reinforcement in a working platform of coarse-grained material on soft lacustrine clay.
The experiment was supported by various measuring instruments to collect detailed performance data under real load conditions during pile driving operations. A laid and welded geogrid installed at the base of the working platform was equipped with strain gauges to monitor the tensile forces mobilized during specific phases of loading by the piling rig. In addition, earth pressure sensors were installed both directly under the chains of the piling rig and below the geogrid at the interface between the reinforcement and the subgrade to measure the vertical stress distribution across the platform system. Multipoint settlement gauges placed closely beneath the crawler tracks monitored the settlement as well as differential settlements providing insights into the deformation of the working platform and the stability during operation.
The boundary conditions of the field test and monitoring results are presented and discussed. The results are compared with the predictions from the BR 470 guideline for working platforms to gain insights into their applicability for soil conditions from the soft lacustrine clay.
This study contributes to the development of performance-based design methods for temporary working platforms on soft, cohesive soils to improve reliability, safety, and material efficiency. The results provide important input for refining current design approaches and supporting the broader adoption of geogrid reinforcement in temporary working platforms.