Installation of Downdrag Instrumentation on a Bridge Abutment Foundation: Lessons Learned

This project involved placing instrumentation on driven piles used on a bridge abutment in order to monitor downdrag effects due to negative skin friction. The overall scope included placing vibrating wire strain gages on a number of closed-end steel pipe piles and measuring the change in strain in the piles with time as consolidation occurred due to placement of backfill material after the pile driving process was completed. The instrumentation allowed the magnitude of downdrag forces to be monitored, providing field data as to the negative skin friction acting on the piles. It also provided the opportunity to compare the response of Teflon-coated piles versus uncoated piles. Having instrumentation on a variety of piles has provided a valuable collection of data that will offer better insights into the downdrag phenomenon. The purpose of this paper is to share some lessons learned in the instrumentation process and to provide insights to others as additional research occurs in the future.