Load Reduction on a Rigid Pipe: Pilot Study of a Soft Cushion Installation

TLDR: In this paper, an 800mm pipe was built on a cushion of expanded polystyrene under an embankment fill of 9.3 m. The results indicated that the safety margin in the design was greater than first expected because the reinforced standard pipe, designed for only 5 m of fill, was uncracked.

Abstract: In a project involving the construction of a new link of European Freeway E18, an 800-mm pipe was to be founded on a cushion of expanded polystyrene under an embankment fill of 9.3 m. In a pilot study measurements were taken of soil-pipe contact earth pressures around the circumference of the pipe, vertical earth pressures in the soil above the crown, relative diameter changes of the pipe in the vertical and the horizontal directions, and pipe settlements into the cushion. The design of the complete structure was partly done by using the active design program SPIDA (Soil Pipe Interaction Design and Analysis). The results indicate that the safety margin in the design was greater than first expected because the reinforced standard pipe, designed for only 5 m of fill, was uncracked, even though the height of fill was 9.3 m. The measured deformations of the pipe were smaller than those expected for the concrete to crack. The earth pressure measurements showed a pronounced soil arching effect in the soil above...