Design of Geogrid Reinforced Temporary Working Platforms for Tracked Plant - Insights from a Large-Scale Field Trial on Soft Lacustrine Clay-Paper

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The study reports a large-scale field trial of a geogrid-reinforced working platform constructed over sensitive lacustrine clay in southern Germany. The platform comprised a separation geotextile, a laid-and-welded geogrid, and a 0.3 m layer of compacted crushed dolomite. A 66-tonne tracked piling rig performed representative lifting, rotating, and pile-pulling manoeuvres.<br /><br />Instrumentation measured geogrid strain, vertical earth pressure at the platform and subsoil interfaces, and settlement. During the monitored operations, localized pressures reached approximately 240 kPa and settlements reached about 40 mm, with visible rig tilting. Despite these substantial loading and deformation effects, measured geogrid strains remained relatively limited. The results suggest that the comparatively stiff surface crust of the clay subgrade restricted mobilization of the geogrid’s tensile capacity, even though weaker layers occur at depth.<br /><br />The trial illustrates how rig manoeuvres can cause rapid, localized shifts in loading, including simultaneous loading and unloading beneath nearby parts of a track. The reinforced platform was nevertheless essential: operating directly on the clay would likely have caused severe rutting, tilting, and vibration. Testing took place during intense rainfall.<br /><br />These preliminary findings will support finite-element model validation and evaluation of the BR 470 design guideline. Future work will focus particularly on serviceability—such as excessive settlement and equipment tilting—rather than geogrid rupture, with the broader aim of developing more performance-based design methods for platforms on soft cohesive soils.

Keywords

geogrid-reinforced platform

field trial

lacustrine clay

southern Germany

tracked piling rig

vertical earth pressure

geogrid strain

settlement

serviceability

finite-element model validation