BUILDING REPORT FOR SCHWARZE PUMPE INDUSTRIAL AREA
(Salzburg / Kalbach, in October 2013)
In this process special steel pipes with lateral outlets and tip are rammed into the soil. Suitable extensions are available with and without outlet openings. Especially suitable for low depths in well penetrated soil. The maximum embedment depth is dependent on the ground conditions. In practice, it is possible to embed at depths of up to 15 meters. The injection material may penetrate the soil through the openings. When injecting under base plates these have to be pre-drilled accordingly. For sealing the packers are used with a coupling sleeve.
Drinking water reservoir 1 and 2 on the area of the "Schwarze Pumpe industrial area" have a storage space of 2800 cubic metres each. They were built in the period from 1989 to 1991 as standardized projects (series "PROWA").
The overhead tanks are free-standing round containers with an outside diameter of 25.88 meters and a ceiling height of 6.00 meters. They were manufactured in a mixed structure, usually as a reinforced concrete structure.
Monolithic construction: ring container foundations, lower foundations, container floor with a berm formation in the wall area. Erection of buildings: container wall, supports and upper sealing construction. The container floors were constructed from in-situ concrete (B 20) with a soft steel reinforcement. The entire floor plate area was thus formed with both radial and diagonal joints (transverse joints). The container bottom is approx. 1.50 meters above ground level. This means that the plate surface was refilled during the construction phase.
After water leaked from the drinking water reservoir 1 to the outer area, an internal investigation was carried out following the emptying of the reservoir with the following results: leaking joints were found in parts of the container edge areas between the berm and the foundation ring. A ground subsidence was found in the berm plate area next to an obviously crumbling transverse joint, due to erosion / flushing in the floor area below the tank bottom as a result of leaking joints.
The required restructuring planning was implemented by Kiwa MPA Bautest GmbH, Lausitz Service Centre. Prior to the renovation of the crumbling joint, the lowered underground in the berm plate area needed to be solidified in order to avoid further sinking of the ground in this area. As mentioned previously, the foundation soil is, backfill or refill material (certainly gravel mixture). The following steps were planned for this process:
- Drilling of injection channel for the intended ram injection lance at intervals of about 50 cm x 50 cm vertically through the concrete base plate.
- Following the vacuuming of debris and dust from the injection channels - the injection lances are rammed into the ground.
- Product: ram injection lance from DESOI GmbH, type: BP-complete, diameter 25 mm x 1200 mm.
- Sealing and consolidation of ground injection by injecting a low viscosity polyurethane-based duromer resin manufactured by MC-Bauchemie with a 2-component injection pump over the previously introduced ram injection lance.
- After the injection material has hardened, the steel packer is removed and the concrete surface is repaired.
The construction work was carried out by the company MBS MAERTIN, Bausanierung Spremberg GmbH. The construction work was carried out professionally in accordance with the restructuring plan incl. specifications. In addition to the ground consolidation, the general restructuring / repair of all crumbling joints are included. The implementation of the construction was controlled on site by the planner and the client.
After the acceptance of the construction work with a positive leaking test after having filled the reservoir, the reconstruction measures, incl. ground consolidation by the ram injection lance, were completed successfully.