Challenge

The project consists of six temporary critical walls necessary for the installation of MSE walls, temporary shoring entailing steel sheetpiles and 430 temporary post tensioned tiebacks with wale as well as 14 phase-one micropiles with maximum lengths of 66ft with a maximum load of 239 tons.

Solution

ASAP performed successful verification tests to a load of 478 tons and four successful proof tests to 130 tons. Hard driving conditions and tight a schedule. Sheet piles needed to be driven through hard limestone.  ASAP first drove the piles as deep as possible using a vibratory hammer followed by its hydraulic impact hammer to drive the remaining pile length to minimum tip elevation.  Thanks to ASAP’s specialized equipment, predrilling was not required to drive the sheet piles, which would have been required with any regular industry pile driving setup.  ASAP’s performance is saving significant time in the installation process. Additional challenges encountered included limited work area and access for the micropiles and tiebacks installation around existing structures and utilities while supporting an active highway.  ASAP coordinated with the contractor to make the piles at pier 2 and pier 3 available at once and worked an extended night shift to install two piles per shift by moving between piers during the lane shutdowns. We also were able to work within the median between the northbound and southbound turnpike to install the micropiles through the MSE wall overburden and into the subgrade soils. Utilizing our MC8D capability and size, we were able to install the micropiles at the designated locations with the limited access constraints.