Numerical investigation of earth pressure reduction on buried pipes using EPS geofoam compressible inclusions

This paper presents a numerical study performed to investigate the effect of expanded polystyrene (EPS) geofoam panels placed over a buried pipe. It is recognized that EPS geofoam panels as compressible inclusions over a buried pipe are effective in reducing the earth pressure acting on the pipe due to positive arching action. To date, however, there is no systematic methodology that links the earth pressure on a buried pipe with the geometry of EPS panels. To investigate the ‘optimal’ geometry of EPS panels, a two-step numerical modeling approach was employed and calibrated against results of a model-scale experimental study. First, material properties were estimated for each component used in the model-scale tests (i.e., soil, EPS geofoam and steel pipe). Second, the model-scale experiments were simulated using the selected material properties. These simulations resulted in reasonable agreement between model-predicted and measured vertical and lateral earth pressures. Using the calibrated model, additional cases that were not covered in the experimental study were investigated to examine different widths and thicknesses of EPS panels. The numerical analysis provided quantification of the effect of EPS compressible inclusion and a systematic approach to optimizing the design of buried pipes using EPS geofoam panels.