An Unknown-Unknown Does in an Overpass: A Soil Stockpile on Soft Clay Is Too Much for a Bridge in Canada

December 14, 2020

Like most structures, bridges are designed for an array of loading conditions. Some loads are known or can be reasonably estimated with confidence (i.e., known-knowns, such as structure dead and vehicular traffic loads). And based on site conditions such as regional seismicity, scour-prone foundation sediments, or downdrag loading from settling foundation soils (i.e., known-unknowns), load conditions can be estimated, albeit with less certainty. But on occasion, a bridge can be affected by a load condition that no designer could have anticipated (i.e., unknown-unknown). This story is about such an occasion. Sy, A. 2019. “An Unknown-Unknown Does in an Overpass: A Soil Stockpile on Soft Clay Is Too Much for a Bridge in Canada.” GeoStrata. 2(23): 62-67.