Two large-span flexible steel culverts in norway were instrumented for monitoring long-term behavior. The first structure was a pipearch with a span of 7.81 M completed in 1982, and the second was a horizontal ellipse with a span of 10.78 M completed in 1985. Both structures are backfilled with high-quality, well-graded dense gravel and sand. The main influence on the long-term effects is likely to be environmental factors such as seasonal temperature and moisture variations. In norway, the winter is very cold and seasonal temperature changes are great. Hydraulic earth pressure cells of the glotzl-type are used on both structures, and thermistors are used to measure temperature variations. In addition, strain gauges are mounted on the horizontal ellipse to measure stress changes in the steel structure on a long-term basis. The long-term observation of the flexible steel culverts in this study shows that they undergo changes in earthpressure distribution and structural response as time progresses after construction. On both structures, the horizontal earth pressure at the springline has increased to values somewhat above the overburden pressure. The measured thrust force in the steel on the horizontal ellipse increases considerably with time. Although the measured vertical earth pressure over the top of the structure is less than the overburden, the measured thrust stress indicates negative arching for the structure as a whole. This paper appears in transportation research record no. 1231, Analysis, design, and behavior of underground culverts.
Abstract