Analysis of Pile-Supported Embankments that Considers Compatibility of Soil Settlement and Strain in Load Transfer Platforms

This paper presents a structural analysis procedure for load transfer platforms reinforced with flexible geogrids–geotextiles and used for pile–column-supported embankments. Design of these systems must consider strain compatibility between the expected settlement of soils between piles combined with the tensile stiffness and deformation of the reinforcements for the load transfer platforms. When relatively small settlements are expected, significantly stiffer reinforcement materials are necessary to transfer greater loads to piles at lower levels of reinforcement strain and settlement. This simplified analysis procedure uses theory on uniformly loaded cables for the calculation of reinforcement elongation and force mobilization caused by deformation occurring between piles, while using site settlement estimates and a specified curve for geogrid–geotextile force versus strain. The analysis procedure considers both a soil-arching load case and a tributary block load case. The procedure allows for rapid estimation of the strength and stiffness requirements of the reinforcements for load transfer platforms and of pile loads for designs. An example problem simulating an embankment 40 ft tall overlying soft soil is provided. Sensitivity analyses demonstrate how variations in pile spacing, embankment height, subsoil compressibility, and reinforcement stiffness affect the predicted behavior of the pile-supported embankment.