Influence of Clay Compressibility on Geosynthetic Loads in Bridging Layers for Column-Supported Embankments

Abstract

Several different methods exist for calculating the magnitude of loads applied to geosynthetic reinforcement in bridging layers for column supported embankments. These methods take into account such factors as the column or pile cap size, column spacing, embankment height, embankment unit weight, and embankment friction angle. These methods produce loads that differ by a factor of six or more for typical examples. Furthermore, none of these methods take into account the compressibility of the soft ground between the column. This paper reviews the published methods and compares them with the results of numerical analyses. The numerical procedures were calibrated against measurements from the instrumented test embankment at the interchange of US I-95 and Virginia State Route 1 in Alexandria, Virginia. Results of the parametric numerical analyses show that the net vertical loads applied to geosynthetic reinforcement depend on the compressibility of the soft foundation soil between the column. For this reason, the compressibility of the foundation soil should be an important factor in design, even though this is not part of current practice.