Geofoam Bridge Approaches for 11-MN Module

As part of a project to replace an existing power plant within a crude oil refinery in Grangemouth, Scotland, with a new fuel-efficient, hydrogen-ready energy plant, modules weighing over 11 MN had to be delivered and installed in an operating facility that is underlain by soft clay. For the facility to remain in operation during the construction of the new energy plant, the modules had to cross operating pipelines. A pile-supported bridge was constructed over the pipelines. However, the challenge proved to be the design of the bridge approach embankments. Existing underground utilities prevented the use of piles or ground-improvement to support these embankments. Ultimately, expanded polystyrene (EPS) geofoam blocks were adopted as the solution. Given that there was no British precedent for the use of geofoam to support such a large moving load, extensive analyses had to be performed to convince the project of the viability of this geofoam solution. Through refinement of the undrained shear strength profile of the foundation soils, application of numerical analysis to evaluate both stability and deformation of the embankment, and use of full-scale proof-testing, a geofoam embankment design was developed, constructed, tested, and successfully utilized for the installation of the 11-MN modules.