Monitoring of a timber pile-supported road embankment

Abstract

Timber piling allows for a solution with lower carbon footprint than concrete or steel piling, yet there exist few well-documented cases of modern timber piled embankments. In this paper, field measurements on a geosynthetic-reinforced timber pile-supported road embankment are reported and evaluated. The monitored road embankment is a section of a newly reconstructed semi-motorway in northern Sweden. The embankment was constructed on 8 m long untreated timber piles with 1.1 m spacing in a triangular pattern, without pile caps. On top of that, a 1.7 m high embankment was constructed, reinforced by two layers of biaxial geogrids. A long-term monitoring program is being carried out from when the semi-motorway was reconstructed. This study presents results from the first year of monitoring. The measurements include the load on the pile heads and subsoil, geogrid strain, pore water pressures, and settlements. The measurements show the development of arching over time, the interlocking of geogrid and embankment material, the subsoil consolidation, etc. The results of the monitoring are compared with results of analytical models from recommendations and codes.