Delicate foundation soil makes pile driving a challenge
The Frankipfahl NG® piles are inserted vertically and inclined as foundation pilings for two of the bridge abutments. The piles must be driven up to 28 meters deep, which is a challenge due to the sensitive foundation soil. The soil’s sensitivity consists of a layer of sand that forms the load-bearing foundation soil atop which is loose, silty fine sand, sometimes with boulders. This repeatedly causes the pipe to dislocate and thus prolongs the pile driving process. The formation of excess pore water pressure and water-bearing strata must also be taken into account. For that reason, consecutive piles are inserted as far apart as possible, which prevents the freshly driven piles from influencing each other (for the most part) and disturbing the soil.