In the beginning of 2008, we were approached by a leading civil engineering contractor, to undertake a monitoring project to measure movement of a 70 degree reinforced soil embankment during and after construction. The embankment construction was undertaken due to a road widening scheme along the A1081, the main approach to Luton Airport. A conventional embankment with a lesser a gradient was not an option to the designers due to a row of trees that had been designated to be preserved. The embankment is approximately 350m in length, with a maximum height of 10m. Monitoring points were installed at 10m intervals along the embankment, with five targets spread up the embankment at each chainage interval. A ground anchor was driven into the wall at each monitoring point with a retro target fixed to the plate at the end. The points could then be monitored using a total station referenced to control stations installed and separately monitored by ourselves. Initially we began monitoring the embankment weekly, which was subsequently reduced to a fornightly visit after construction had been completed. The results of each visit are analysed by our specialist deformation monitoring software and graphs supplied to the client for their appraisal. Movement is shown as both vertical (settlement) and horizontal. The client also provided us with the horizontal alignment geometry for the new road design, so we are able to report horizontal movement as movement up or down chainage and also by offset. The above shows a graph representing settlement vs time. The different colours represent different monitoring points.

Monitoring - Reinforced Soil Embankment, Luton

NRG Engineering Services Ltd Land and Engineering Surveyors