Abstract: Compared to traditional small-diameter circular corrugated steel plate culverts, there have been few application and research on large-span pipe-arch steel corrugated plate culverts (PACSPCs) in subgrade engineering. Relying on a certain expressway project in Yan’an City, the field test scheme was elaborated in detail, and the mechanical characteristics of a rarely-seen PACSPC with a span of 9.5 m and a rise of 6.5 m during the embankment backfilling were tested. Numerical simulation was adopted to further study the influence of pipe parameters on its mechanical characteristics. The coefficient of soil arching effect Mf was introduced, combining orthogonal experiments and numerical simulations, and an earth pressure calculation model for large-span PACSPCs considering the soil arching effect was established. Finally, the accuracy of the calculation model was verified through the field test results. The results show that during the backfilling, the vertical deformation of the pipe is greater than the horizontal deformation. At the same position, the stress at the wave trough is greater than that at the wave crest. The existence of the soil arching effect makes the earth pressure on the top of the pipe and the settlement both show a V shape distribution. During the backfilling, the deformation at the top of the pipe is the largest, which is 36.1 mm. It meets the specification requirement that deformation should not exceed 2% of the span. However, the designers should pay particular attention to the stress design at the wave trough at 90° on both sides of the pipe. The bolt splicing positions of the pipe are recommended to be set near 30°, 180°, and 330° clockwise around the pipe. Increasing the corrugation size and the thickness of the steel plate can reduce the deformation and stress of the pipe to a certain extent, but the cost and material characteristics should be comprehensively considered in the design stage. The calculation results of the established theoretical model are in good agreement with the field test results, effectively reflecting the earth pressure distribution on the upper part of the large-span PACSPC. The research results can provide a reference for the design, construction, and theoretical analysis of large-span PACSPCs.

Key words: corrugated steel plate culvert, large-span, pipe-arch, mechanical characteristics, calculation of earth pressure