Civil and Environmental Engineering student and faculty researchers are working on a North Carolina Department of Transportation project to determine the axial bearing capacity of steel sheet piles used in short span bridges.
Using the geotechnical pit in the high bay laboratory of the Energy Production and Infrastructure building, the team has installed sheet piles instrumented with strain gages, strain transducers, and accelerometers to monitor the behavior of the piles during driving and for axial compression load testing.
During the summer of 2014, the researchers backfilled the geotechnical pit with compacted silty sand and carried out several in-situ tests to characterize the compacted soil and measure relevant geotechnical properties. The in-situ tests included SPT, CPT, MASW, and Cross-hole seismic testing.
After backfilling the pit, the team installed two rows of PZ-27 steel sheet piles. The installation required an impact pile driving hammer, as well as a vibratory hammer. The first row was installed on July 29th and the second row was completed August 19th.
The team has now constructed a load frame above the installed sheet piles to do the dynamic and static loading test with a 220 kips hydraulic actuator. The load frame, so called Geotech Portal, is designed for the 300 kips total vertical load.
This ongoing project has benefited from technical and material support from several companies including (in alphabetical order): GRL of Charlotte, Hayward Baker, ICE of Matthews, Lee Carolinas, S&ME of Charlotte, and Skyline Steel. Their support and assistance is greatly appreciated and acknowledged by the research team.
A photo gallery of the work to date is here: