Construction Engineering: Onshore Pile Tests for OWF Dugeon
NGI has been asked by Statoil to plan and execute field tests to evaluate options for reduction of pile driving resistance in a very stiff clay as encountered at the Dudgeon site offshore UK. The objectives for the field test is to investigate the effect of using different types and combinations of oversized driving shoes (inside and outside) to reduce shaft resistance during driving through such stiff clays. The aim is to demonstrate that the penetration resistance can be reduced to agreed target value without any significant effect on the lateral stiffnes of the pile (caused by possible gap created by the driving shoe). This should include planning for some smaller scale pile driving tests in a similar clay deposit at a convenient site on land. A suitable test site has been found in Rødbyhavn at the Danish side of the planned new fixed link across the Fehmarn straight between Denmark and Germany. This site consists of a very hard stiff silty sandy Clay till (Moræneler) and has been made available for test execution by the owner Femern A/S. Bilfinger Construction (BMOS) has been awarded the contract for
- delivery of six piles (DU 1220, L=10m, weight 7t) incl. driving shoes (specifications by client)
- design and fabrication of a lateral load test structure
- piling operation
- performing lateral load testing
- Decommissioning piles (removal)
Technical data / main masses: Pile driving (6 piles), Lateral Load Testing (5 runs), Extraction of 6 piles.