Piles Innovations: Deep bored Piles for a hotel extension in the heart of Brussels-Paper

Paper

Pdf Summary

The Crowne Plaza hotel extension in central Brussels demonstrates how deep foundations can be constructed in a confined, sensitive urban setting. Work took place beside an operating five-star hotel and above an underground metro, with very limited space for equipment, storage, and site circulation.<br /><br />The design used bored piles approximately 50 metres deep, founded in dense Landes sands. Pile sizes and arrangements were tailored to the building’s high loads and cantilevered structure over the metro. Jet-grout columns helped protect the existing hotel’s wooden-pile foundations from settlement, while flat jacks were installed to manage settlement during construction. Piles near the metro wall were carefully detailed and partially cased to reduce ground loss and potential interaction with existing structures.<br /><br />Drilling was carried out with polymer support fluid, which stabilized boreholes and avoided the need for a space-intensive desanding plant. The polymer also reduced disposal impacts compared with bentonite sludge, subject to treatment and checks before discharge. For the first large-scale Belgian application of its kind in deep foundations, the pile concrete replaced 30% of natural aggregates with recycled concrete aggregates. Mix design and handling were adapted to preserve fluidity and workability for up to four hours.<br /><br />The project achieved the required quality and productivity despite substantial spatial, geotechnical, and structural constraints. It illustrates how tailored drilling methods, careful settlement management, and recycled materials can help deliver technically demanding foundations while addressing environmental requirements. Its experience offers guidance for similar projects in dense urban areas.

Keywords

Crowne Plaza Brussels

deep foundations

urban construction

bored piles

jet-grout columns

polymer support fluid

settlement control

recycled concrete aggregates

metro proximity

geotechnical engineering