Working Platforms for Tracked Plant - A New Design Method Including Multiaxial Geogrids-Paper

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The paper presents a design method for granular working platforms supporting tracked piling rigs and other heavy plant. These platforms must prevent bearing failure and equipment toppling, but conventional methods often represent geogrid benefits using tensile strength measured in air. That approach is unsuitable for multiaxial geogrids, which primarily stabilise aggregate by restraining particle movement.<br /><br />The proposed T-value method models failure as punching through the granular layer into the underlying clay. The T-value represents the layer’s load-transfer efficiency and links platform bearing capacity to geometry and subgrade strength. Researchers derived these relationships through finite-element analysis (FEA), informed by large-scale triaxial tests of aggregate with and without geogrid. These tests showed that geogrid stabilisation changes the aggregate’s shear-strength behaviour. The resulting constitutive model was used to simulate the aggregate–geogrid composite.<br /><br />For one specific crushed-rock and multiaxial-geogrid combination, FEA established a relationship between T and clay undrained shear strength. The method can account for different foundation geometries, including strip, square and circular loading, and was supported by published research and centrifuge tests. A field plate-load test on a 0.4 m-thick stabilised platform over clay reached about 90% of the predicted ultimate bearing capacity without observable failure, providing additional validation.<br /><br />The authors stress that the T-value relationship is specific to the aggregate and geogrid product: similar materials cannot automatically use the same design parameters. Other combinations require appropriate large-scale testing, FEA parametric studies and full-scale validation. The method offers a research-based alternative to conventional guidance and may enable thinner platforms, reducing aggregate use and excavation while maintaining safety.

Keywords

granular working platforms

tracked piling rigs

bearing capacity

geogrid stabilization

T-value method

finite-element analysis

aggregate reinforcement

clay subgrade

punching failure

field plate-load test