There was a planned residential building with underground garages in Krakow, Poland. The construction of a multi-storey residential building was part of the second stage and required a deep excavation for a two-story underground car park in unfavourable conditions such as a high groundwater table and a thick layer of compacted gravel. The excavation to a depth of -11.5 m with a high groundwater table at -3 m.
During construction, the sealing of larssen sheet piles was inadequate in some places. The sheet piles were used to secure a deep excavation and were 15 meters long. In some places, the locks on the sheet piles were not tightly fastened, and as a result, groundwater began to leak through them, making it impossible to concrete the foundation slab.
In some places, the opening on the locks was up to 10 cm, the groundwater pressure was very high and they needed to be sealed. Due to the presence of obstacles in the ground in the form of a thick layer of compacted gravel, which generated high resistance to driving, the sealing of the sheet piles faltered and detachment of the locks with significant deformation of the sheet piles occurred,
The gaps between the sheet piles were over 40cm wide. With such a deep excavation with a high groundwater table, the general contractor was not able to make the excavation to the target depth without the risk of flooding the entire site.
Geopolymer injections were used tightly on the locks and behind the sheet pile – a welder burned a hole in the sheet piles, whereby we could make an injection behind the lock. In total, we sealed 7 locks, thus enabling the General Contractor to carry out further works related to the installation of reinforcement and concreting of the foundation slab.
Geopolymer injections performed before and after securing the excavation permanently stopped the inflow of groundwater.
Geobear regularly provides emergency water sealing works as our geopolymer material forms a water barrier to prevent water migration. Thanks to the use of geopolymer injections, on the critical path of the construction schedule, the problem that influenced potential delays throughout the contract was solved. The contractor and the investor saved time and financial resources.