Firms working on the $670-million Mississippi River Bridge in St. Louis have shattered geotechnical records related to one of the bridge’s drilled-shaft concrete foundations while verifying a time-saving, alternate pier plan. Photo: Courtesy MTA Joint Venture Record-breaking load cell makes its final descent at St. Louis. The test, performed this past June, consisted of drilling an 11.5-ft-dia shaft 43.5 ft under the riverbed, then cutting an 11-ft-dia socket more than 23 ft into the underlying limestone bedrock. An Osterberg load cell then was lowered to the bottom of the rock socket, and reinforced concrete was poured into the hole. When
Arch dams, classically curved monoliths situated in narrow valleys, are not as common as other types of dams, such as embankment dams and gravity dams. ENR takes a look at some of the biggest arch dams in the world, both completed and under construction.