Construction of the excavation pit and driven pile foundation for the new building of the Technical Town Hall in Mannheim.
The enclosure of the excavation pit was carried out by means of a single-layer tie-back beam shoring with timber and shotcrete infill. The girders were inserted into the ground by means of a Kelly borehole after prior exploration for explosive ordnance. Subsequently, the space between the girders was filled with wooden planks down to a depth of 1.50 m below ground level. The area below the 1.50 m to excavation base (approx. 4.50 m below ground level) was secured with a shotcrete shell. The shoring was anchored back with a layer of grouted anchors, each with 2 to 4 strands.
The foundation for the later structure was made by means of 635 prefabricated reinforced concrete piles driven up to 18.00 m deep into the Mannheim subsoil. The majority of these piles were driven at an angle to form 3 and 4 pile trestles. Here, too, an explosive ordnance probe was first carried out.
In addition, four foundation piles for a revolving tower crane were driven using the Kelly drilling method.