For a demanding contract in Emden, Lower Saxony, the Stump-Franki team from Oldenburg literally outdid themselves under extremely limited space conditions: for the subsequent pile foundation of two machine foundations, 51 foundation piles up to 27.50 m long had to be installed in a hall with heights between 12 and 15 metres. The structural analysis of the external pile load-bearing capacity was carried out by Stump-Franki Planung.
Pile system meets high requirements for load settlement behaviour
The machine foundations each have an area of 25 x 15 m and serve as a stable foundation for two powerful grinding machines. After commissioning, precast concrete parts will be processed here with high precision, so the requirements on the load settlement behaviour were correspondingly high. The foundations had to be founded independently of the existing floor slab in such a way that settlements and deformations were practically excluded. "Instead of driven steel pipe piles with a smooth shaft, we therefore recommended helical atlas piles with pile diameters of 41 and 51 centimetres to the client," explains Lars Brömstrup, Branch Manager Foundation Engineering Competence Centre, and continues: "These full displacement piles have a significantly better load-bearing capacity due to their high skin friction and the compaction of the existing soil during sinking and mean more safety for the client." The lack of soil excavation and the low-noise design also had a positive impact as an economic solution.
Tight space conditions demanded all the skills
Due to the limited working heights, the drill pipes were inserted in several shots and the reinforcement cages were pushed several times. The load-bearing subsoil of medium-dense to densely bedded fine sands was overlain by a mixture of silt and clay as well as gravel and fine sands. The groundwater at depths between 2 and 4 m is saline due to the proximity to the North Sea. To protect the subsoil from chemical attack and wear, the concrete formulation had to be adapted accordingly. Thanks to years of experience, the team mastered the challenges with flying colours and on schedule.
