Vertical Loads on Concrete Box Culverts under High Embankments

Abstract

Vertical loads on concrete box culverts under high embankments are examined, where a high embankment is defined herein as one where the height of the fill above the culvert is greater than the width of the culvert. Results from an instrumented culvert are described, with results from pressure cells, strain gages in the wall, and strain gages in the roof showing reasonable agreement. There was strong correlation between the height of fill and the pressure and internal forces in the culvert, suggesting that the soil–structure interaction factor is independent of the H∕B ratio. The results of the instrumented culvert were compared to those of other instrumented culverts under high embankments. The measured roof pressures were significantly greater than the pressure due to the soil overburden, with the measured pressures averaging 1.5 times the soil overburden pressure. Although the soil–structure interaction factor recommended by the American Society of Highway and Transportation Officials specification tends to under-predict the loads acting on concrete culverts, a simplified reliability analysis suggests that the Specification provides a sufficient level of safety.