Marienplatz München

Short description

As part of the construction of the second S-Bahn underground railway line in Munich, the Marienhof stop is being built directly behind Munich's town hall using the cut-and-cover method.

The project

The outer supporting structure is a 55m deep peripheral slurry wall consisting of 104 individual sections and two 3-section T-diaphragms. In order to meet the exceptionally high requirements for accuracy and impermeability, a milled slurry wall was constructed with a specially configured, project-specific, steerable cutter. Due to static and geometric constraints, individual sections had to be constructed. The lamella width is 3.20m, the wall thickness 1.50m. Due to high static loads, the great depth of the excavation pit with large spans between the ceilings and low permissible deformations, exceptionally high reinforcement contents (3-layer, up to 40mm bar diameter, multiple joints) with cage weights of up to 47 tons were used. The intermediate support of the 5 slabs and the base plate within the diaphragm wall box is provided by primary supports made of solid 44 m long multi-part steel box sections with 24 m long foundation piles under the bottom of the excavation pit. The boreholes, which were up to 68 m deep from the top of the ground, were partially cased. The upper 20 meters of drilling were cased with a drilling diameter of 2.0 m. Uncased drillings with a diameter of 1.8 m were made to the deepest point of the borehole. The structure has a base area of approx. 52 m x 100 m and will be constructed to a depth of 40 m below ground level, resulting in an excavation and disposal volume of more than 200,000 m³ under the covers and ceilings. In addition to the work described above, further special civil engineering works will be carried out as part of the overall project. These include drilling pile works, clearing drilling, anchoring, sheeting and jet grouting works. For the stabilization and possible height correction of the sensitive neighboring buildings, including the adjacent subway lines U3 and U6, extensive injection screens and compensation measures will be carried out in the course of further excavation from the slurry wall box. The water drainage system in the inner and outer areas, consisting of more than 100 wells, serves primarily to relieve the pressure of the water table in the Tertiary and to relieve the diaphragm wall box. The construction project is monitored by a large-scale geodetic and geotechnical measurement program. The two platform tubes will later be driven from the structure using compressed air and mining methods. The platforms, technical rooms and distribution levels, as well as the transport routes, will be constructed within the slurry wall box.