The project
The Mogilska Office building was executed by PORR as a general contractor. Keller Polska offered and performed geotechnical works connected with securing a deep excavation using its own solution.
The challenge
The biggest challenge was the optimal design and timely execution of complex geotechnical works, in difficult ground conditions, in the immediate vicinity of existing buildings. An additional difficulty during the execution was the more than 200 piles existing in the ground, which constituted an intermediate foundation of the previously demolished building.
The solution
A 60 cm thick diaphragm wall was used to strengthen the walls of the building excavation with a circumference of about 300 m and a depth of 8.2 to 10.4 m. The stability of the diaphragm wall in the construction phase was secured by two levels of a temporary steel expansion structure. The total weight of the temporary expansion structure was almost 300 t. In the vicinity of the existing buildings, an additional support of the diaphragm wall in the form of a ceiling above storey "-2" was applied. In the construction phase, the floor was supported by barettes and temporary columns. Anchoring of the foundation slab for buoyancy was carried out by means of 15 0.6 x 2.8 m barettes reinforced with a basket. The foundation of two tower cranes was also made in the horizontal ceiling "0". Keller carried out its work from September 2017 to June 2018.
