Full-scale field study of using geofoam to reduce earth pressures on buried concrete culverts

Applications of geofoam for buried culverts/pipes keep increasing; however, the design of such applications is still challenging due to lack of full-scale studies. Considering practice needs, a full-scale field study was carried out to investigate the effectiveness of different geofoams with different layouts to reduce overburden stresses on deeply buried, large-size culverts. Among the eight test sections, five were installed with two different of geofoams (7.5 and 15 kg/m3) in thicknesses of 300 and 600 mm and the remaining three were built with loose sand, lightly and normally compacted clay, respectively. The acquired data indicated that the geofoam can greatly reduce the overburden stress over the culvert. In general, higher compressibility of geofoam resulted in greater stress transfer but did not cause excessive settlement at the surface due to significant burial depth. However, due to its large span and dome shape, a secondary soil arching formed when the soil over shoulder settled more than that over the crown, which readjusted the stress and resulted in further reduction in the stress at the culvert shoulder but partially compromised the stress reduction at the crown. Such phenomenon shall be appropriately addressed to avoid unexpected damage to buried culverts or pipes.

Automated summary

The increasing application of geofoam for buried culverts/pipes poses challenges in design due to lack of full-scale studies. Research shows that geofoam effectively reduces overburden stress on deeply buried culverts, but secondary soil arching should be addressed to avoid unexpected damage.