Reduction of Earth Pressure on Buried Pipes by EPS Geofoam Inclusions

This paper presents the experimental study that investigated the applicability of compressible inclusion, expanded polystyrene (EPS) Geofoam panels, placed over a buried pipe. A series of model tests was conducted to identify the optimal EPS geometry. The tests employed multiple sections of EPS for imperfect ditch condition. Full-scale tests were also performed to calibrate the reduction in earth pressure due to the placement of double layers of EPS. In the model tests, one layer of EPS Geofoam reduced the vertical earth pressure acting on the pipe up to 73 % depending on the width of EPS. Double layers of EPS could induce the reduction of vertical earth pressure on the pipe as much as 71 % and horizontal earth pressure on the pipe about 60 % depending on the spacing between Geofoam inclusions. The full-scale test results indicated that the magnitude of the vertical pressure decreased by about 31 %-36 %. In case of horizontal pressure, 37 % reduction was observed for double layers of EPS while only 5 % reduction was found for a single layer of EPS. This study demonstrates that multiple layers of EPS provide better solutions in reducing the earth pressure on a pipe.