Scope of Project:
Brayman was awarded a contract for the construction of instrumented test caissons at the site of this newly designed gated dam. Utilizing the Osterberg Cell methodology, two test caissons were installed in the middle of the Monongahela River. The intent of the contract was to test caisson installation methods and determine design parameters in order to finalize the caisson and rock socket length design.
The two Osterberg cell shafts were built in the river to test the rock socket depth necessary to sustain the required load. The tests concluded that a 5 foot depth was sufficient for the load factor versus the alternate 15 foot depth. The 5 foot depth proved to sustain up to 3,300 tons - almost twice the value previously assumed adequate for design. Project savings were driven by eliminating the expense of drilling the additional 10 feet of rock socket for the caissons needed to construct the new Braddock Dam.
Brayman’s work consisted of installing, instrumenting and testing 60” diameter drilled shafts; all from a floating plant. A significant part of the contract involved site preparation including dredging, and the design and installation of work platforms and templates in the Monongahela River.
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