Petersberg
"Michael" bastion
Erfurt, Germany / 07.2014 - 10.2014
At the ‘Michael’ bastion on the Petersberg in Erfurt, restoration work was carried out on a historic retaining wall. The wall showed signs of localised deformation as well as several areas of spalling. To repair and structurally stabilise the wall, measures were implemented to stabilise the slope, carry out grouting and repair the masonry.
Facts & Figures
Company
PORR Spezialtiefbau GmbH
Type
Rehabilitation
Runtime
07.2014 - 10.2014
Static stabilisation of a retaining wall by means of Soil nailing
Rehabilitation of a historic retaining wall
The ‘Michael’ bastion forms part of the historic fortifications of the Petersberg in Erfurt. During condition surveys, deformations in the masonry as well as spalling in the area of the retaining wall were identified. To stabilise the structure, the damaged areas were exposed and subsequently repaired.
Soil nailing and grout-filled piles for slope stabilisation
Once the damaged sections of masonry had been removed, the slope behind them was stabilised. This was achieved using boreholes and grout-filled piles, which secure the overlying earth and transfer the loads into the subsoil. The stabilisation measures were carried out in the damaged wall sections as well as in the area of an existing bulge in the masonry.
Restoration of the natural stone masonry
Once the subsoil had been stabilised, the damaged sections of the wall were restored using natural stone masonry. The voids behind the masonry were then filled by means of grouting. In this way, the renovated sections were reintegrated into the existing structure.
Stabilisation of buttresses and the wall coping
The existing buttresses were also stabilised using grouted piles. Larger-diameter boreholes were used for this purpose. In addition, voids behind the masonry were backfilled. In the area of the wall coping and the adjacent wall sections, damaged and partially spalled joints were repaired to preserve the existing building fabric.
Injection work for the masonry restoration
The injection work served to fill existing voids within and behind the masonry. This stabilised loose areas and improved the cohesion of the masonry. These measures complemented the mechanical stabilisation provided by grouted piles and Soil nailing.
The basis for the preservation of the ‘Michael’ bastion
The combination of soil nailing, grout-injected piles, injection works and natural stone masonry created the conditions necessary for the restoration of the historic retaining wall. These measures served to secure and preserve the ‘Michael’ bastion on the Petersberg in Erfurt.