During project development for construction of interstate 94, northeast of miles city, montana, several alternatives were evaluated regarding perpetuation of two large drainages under extensive fills.The alternative selected consisted of installing two structural steel plate culverts. These culverts used the yielding seam concept to relieve the load on the structure by providing controlled slippage in the longitudinal lapped seams. The subsequent reduction in pipe circumference would allow the soil to carry a portion of the load, therefore allowing a reduction in plate thickness and material savings as compared to a conventionally designed structure. Use of this product, relatively new to highway construction applications in 1983, was approved as an experimental feature. Experimental status required preparation of an acceptable work plan, including monitoring of fillsettlements, fill pressures, pipe diameter changes, and strain gauge measurements. The purpose of this experimental feature was twofold. First, a reduction in plate gauge was intended to reduce pipe material costs, yet still provide a structurally sound installation. Second, it would be beneficial to monitor and obtain measurements of earth pressures generated in highway fills of this nature. The measurements would allow coparison of actual fill pressures generated versus design pressures as computed by standard methods and procedures. Additionally, information regarding settlement of foundations under high fills, pipe strain measurements, and pipe diameter changes could be obtained. Reduction in vertical loads was realized as a result of seam slippage, and the installations have performed as expected and as designed. A discussion of the site and installation, instrumentation procedures and observations, and data obtained and recommendations for future projects of this nature are contained within. This paper appears in transportation research record no. 1231, Analysis, design, and behavior of underground culverts.
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