Walnut Street Tunnel

Walnut Street Tunnel

This Project was challenging and exciting. It required new approaches that had never been done before.  Here is the form around the steel column that needed to be repaired.

The consistency and ultra-smooth flow of Steelike® UHPC enabled Steelike to adjust the workability of the UHPC to easily flow through a 4-foot long, 6-inch diameter tremie hose which was reduced to a 75 foot 4-inch diameter for placement without any degradation in the mechanical properties – another first for UHPC.

The first challenge was how to get the UHPC down to the forms which were next to live train tracks.  The solution was to use a 70-foot tremie from the bridge above.  The same Ready-Mix truck that mixed the UHPC onsite was also used to place the UHPC into and through the tremie to the forms below.

Here you see the 50 plus forms that encased the future preserved steel columns.  Again, because live trains were within 20-feet, mixing in the SEPTA tunnel was not an option.

The Finished Product

The results speak for themselves.  All of the 50+ 3-yard encasement blocks were partially reburied and the steel support columns are now protected.  

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