Soil mixing method is environmentally and resident friendly
A total of 1360 m² of construction pit walls up to around 11 m deep and 60 cm thick were constructed using the soil mixing method. In this method, the existing soil is mixed with a binder suspension. This leads to self-hardening of the soil and thus to improved load-bearing capacity. The overlapping of the columns results in a continuous, watertight excavation enclosure. In order to keep the deformations of the shoring wall as low as possible, double U-beams were set into the fresh columns as load-bearing elements. At the same time, they allowed for sectional tiebacks with temporary strand anchors. In order to seal off the construction pits horizontally against the groundwater, the soil mixing walls tie into a low-lying, 1,730 m2 DSV sealing slab. In addition, 70 GEWI micro piles with a diameter of 32 mm, lengths of up to 8 m and durable corrosion protection were produced for the uplift protection of the underground car park floor slab. Due to the minimal soil extraction of the method and the saving of cement, the soil mixing method scores with a low CO2 footprint and reduces transport and disposal costs.
High demands on specialist civil engineering
Permeable gravel and high groundwater levels near the lake placed high demands on the special civil engineering work. In addition, the shoring directly on the property boundary required a great deal of care and sensitivity. Trees, hedges and fences belonging to the neighbouring owners were not to be damaged under any circumstances. "Thanks to our vibration-free, less invasive methods, we took the residents' needs into account as much as possible," explains project manager Sophia Habermann. Since the soil mixing method uses only little cement and minimally extracts soil, Stump-Franki also convinced the client with a sustainable and at the same time economical concept.
