Biblis
Storage facility at the nuclear power station (NPP)
Biblis, Germany / 11.2016 - 02.2017
As part of the dismantling of the Biblis nuclear power station, a storage building was constructed for the interim storage of radioactive waste and residual materials. For the foundation works and the necessary ground improvement, PORR special civil engineering was commissioned to construct large-diameter bored piles as well as full-displacement concrete columns.
Facts & Figures
Company
PORR Spezialtiefbau GmbH
Type
Turnkey construction pits
Runtime
11.2016 - 02.2017
Special civil engineering works for a warehouse building at the power station site
Large-diameter bored piles and ground improvement at the Biblis nuclear power station site
The construction site for the planned storage building was situated on backfilled land. Ground improvement measures were therefore required before structural works could commence. In addition, a retaining wall was constructed on large-diameter bored piles to the south of the building. The specialised civil engineering works comprised both the pile foundations and the improvement of the ground conditions across the entire construction site.
Large-diameter bored piles for the retaining wall
For the retaining wall to the south, 38 large-diameter bored piles with a diameter of 1,000 mm were installed. The piles reached lengths of 14.20 m. The drilling work was carried out using a rotary drilling rig employing the Kelly drilling method. Due to the groundwater conditions, the piles were constructed under water pressure using the contractor method.
Subsoil improvement over 4,000 m²
Prior to the construction of the warehouse, the subsoil was improved over an area of approximately 4,000 m² using full-displacement concrete columns. A total of 1,243 concrete columns with a diameter of 510 mm were constructed for this purpose. Each column had to extend at least one metre into the stable subsoil. The required bearing depth was monitored using equipment data during the construction process. The average length of the concrete columns was around 7.50 m.
FDP Full-Displacement System
The ground improvement was carried out using the FDP full-displacement system. Two drilling rigs were used simultaneously during construction. Concrete was supplied via two mast pumps. The full-displacement concrete columns were installed across the entire site and form the basis for load transfer for the planned structure.
Foundation works for the storage building
The combination of large-diameter bored piles and ground improvement measures was tailored to the site’s ground conditions. The foundation elements provide the basis for the construction of the storage building within the power station site.
Foundation for LAW 2
The construction of 38 large-diameter bored piles and 1,243 full-displacement concrete columns laid the groundwork for the construction of the LAW 2 storage building. The specialist civil engineering works thus form the basis for further construction work at the Biblis site.
