Alexandra Docks Greenport Hull, UK

Key Achievements

Provided a tailored long term monitoring solution that can withstand underwater conditions.•Design a reliable and robust monitoring technique to demonstrate the tie rod was loaded as required

The project

Getec deployed 8 groups of three strain gauges set 120 degrees apart around tie rods installed between the sea wall and anchor piles.
Monitoring was required during demolition and the excavation of a 4000m2 20m deep basement. The basement is constructed using diaphragm walls with a perimeter of 310m and a 30m depth.

The challenge

The strain gauges had to be installed on tie rods installed under the ground materials brought for the port backfilling, and submerged daily by the Humber river.
The strain gauges were used to measure strain readings which were then processed to obtain load results.

The solution

Stainless steel boxes with curved lips and rubber gaskets were used to seal the strain gauges on the tie rod. Grease was pumped within the box to keep the water out.
Strain gauges were disposed at 120 degrees around the tie road and measured every minute during the tie rod stressing. This allowed to calculate the average load applied during the load testing. This permitted our client to demonstrate the target load was respected.