AS Bestwig till Nuttlar
BAB A 46
Bestwig, Germany / 05.2015 - 08.2016
As part of the construction of the new A46 motorway between Velmede and Nuttlar, the Sengenberg was cut through over a length of around 800 metres. PORR special civil engineering carried out extensive slope stabilisation work to secure the newly formed cuttings. The Stump soil nailing system, a construction method approved by the building authorities, was used.
Facts & Figures
Company
PORR Spezialtiefbau GmbH
Type
Rehabilitation
Runtime
05.2015 - 08.2016
Construction of a slope stabilisation scheme at Sengenberg in Bestwig
Slope stabilisation for a road cutting
The cutting into the existing slope created an embankment which had to be stabilised along its entire length. Stabilisation was achieved using a back-anchored shotcrete shell and a gabion wall cladding in front of it. The maximum height of the slope stabilisation was approximately 24.5 m.
Phased construction of the embankment
The slope cut was constructed in stages. The individual sections were built with berms and steps, each approximately 5 m high. Depending on the terrain, up to five embankment steps had to be constructed. Interim excavation work was carried out between the individual construction phases to continue the construction of the slope stabilisation.
Permanent rock bolts and shotcrete lining
The slopes were constructed with a gradient of around 80°. Three rows of double corrosion-protected permanent rock bolts were used for stabilisation. The rock bolts were generally between 8 m and 12 m in length. To protect the slope, a reinforced shotcrete lining approximately 20 cm thick was applied. This serves as well as to stabilise the slope surface and protect the anchor heads.
Slope drainage
Relief boreholes were drilled to reduce water pressure behind the shotcrete lining. The boreholes were arranged in a 1.0 m × 1.0 m grid. In addition, drainage boreholes approximately 5 m long were used to collect rainwater seeping into the verges. Furthermore, additional drainage boreholes up to 35 m long were drilled at horizontal intervals of around 10 m.
Logistics on a linear construction site
The construction work took place along a section of road approximately 800 m long. The ongoing earthworks required continuous adjustment of the site access routes and material transport. The construction of the individual stabilisation sections was co-ordinated with the earthworks and the construction schedule of the motorway project.
Part of the new A46 motorway
The construction of the reinforced shotcrete embankment and the gabion cladding laid the groundwork for the expansion of the route in the Sengenberg area. The works included slope stabilisation, drainage and embankment stabilisation along the section of the route between Bestwig and Nuttlar.
