Construction World December 2022

ANSE LA MOUCHE DEEP FOUNDATIONS

A nse La Mouche i s a hotel resort development located South West of Mahe, Seychel les . The soi l profi le compri se deep, unconsol idated estuarine depos i ts which pose s igni ficant sett lement ri sk to the development . The final solut ion was 350-600 mm diameter Driven Prefabricated Precast Spun pi les . Spun pi les have high axial and moment capaci ty and are sui table for the project condi t ions . Thi s i s the fi rst use of Spun pi les in Southern Af rica. The geotechnical profi le cal led for precast pi les to var ying depths of up to 27 m. The typical square precast pi les manufactured in the Seychel les are not economic and have hi storical ly had qual i ty control i ssues . The suggest ion to use the Malays ian manufactured prestressed hol low precast ci rcular spun pi les set us apart f rom the compet i t ion. Thi s solut ion proved more cost ef fect ive despi te the shipping. Thi s was the fi rst t ime that the solut ion was used in Seychel les . The project faci l i tated communi ty involvement during the construct ion phase; Kel ler employed between 20 and 25 people during the course of the works – up to 15 being f rom local communi t ies . The rai s ing of the general plat form combined wi th the unconsol idated sediments resul ted in s igni ficant sett lement and down-drag to the pi les . In order to minimi se the ef fects of down-drag, the

pi les were sl ip coated in the upper thi rd or hal f. The sl ip coat ing debonded the pi le f rom the surrounding soi l , thereby reducing the down-drag forces on the pi les . Spun pi le sect ion are mass manufactured in factor y envi ronment which al lows reduced costs as wel l as high qual i ty sect ions . Despi te the shipping t ime and costs , the use of the spun pi les ul t imately provided the requi red financial and qual i ty assurance benefi ts for the project . The project was carried out during height of the COVID-19 pandemic. Shipping and logi st ics were extremely di srupted and uncertain during thi s period and posed a s igni ficant ri sk to the project . To mi t igate thi s ri sk , i t was decided that part of the project be founded on tradi t ional Franki type enlarged base pi les for which the equipment was avai lable. 

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