ANSE LA MOUCHE DEEP FOUNDATIONS
A nse La Mouche is a hotel resort development located South West of Mahe, Seychelles. The soil profile comprise deep, unconsolidated estuarine deposits which pose significant settlement risk to the development. The final solution was 350-600 mm diameter Driven Prefabricated Precast Spun piles. Spun piles have high axial and moment capacity and are suitable for the project conditions. This is the first use of Spun piles in Southern Africa. The geotechnical profile called for precast piles to varying depths of up to 27 m. The typical square precast piles manufactured in the Seychelles are not economic and have historically had quality control issues. The suggestion to use the Malaysian manufactured prestressed hollow precast circular spun piles set us apart from the competition. This solution proved more cost effective despite the shipping. This was the first time that the solution was used in Seychelles. The project facilitated community involvement during the construction phase; Keller employed between 20 and 25 people during the course of the works – up to 15 being from local communities. The raising of the general platform combined with the unconsolidated sediments resulted in significant settlement and down-drag to the piles. In order to minimise the effects of down-drag, the
piles were slip coated in the upper third or half. The slip coating debonded the pile from the surrounding soil, thereby reducing the down-drag forces on the piles. Spun pile section are mass manufactured in factory environment which allows reduced costs as well as high quality sections. Despite the shipping time and costs, the use of the spun piles ultimately provided the required financial and quality assurance benefits for the project. The project was carried out during height of the COVID-19 pandemic. Shipping and logistics were extremely disrupted and uncertain during this period and posed a significant risk to the project. To mitigate this risk, it was decided that part of the project be founded on traditional Franki type enlarged base piles for which the equipment was available.
PROJECT INFORMATION
• Company entering: Keller Geotechnics SA • Client: RDC Royal Development Company • Main Contractor: Sanken Contractors • Project Managers: Hooloomann Project Services • Consulting Engineers: WSP in Africa
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21 st Best Project Awards 2022
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