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Design and Construction of a Landfill Containment Bund cum Seawall Supported on
Stone Columns Installed in Very Soft Marine Mud in Cotai, Macau
Conception et construction d’un remblai de depôts avec une enceinte sur des colonnes ballastées
installées dans un sol marin très mou à Cotai, Macao
De Silva S., Fong L.T.T.
AECOM Asia Co. Ltd. Hong Kong.
ABSTRACT: The Cotai Landfill is the main receiving facility in Macau for building construction waste. As the dumping site is
underlain with a thick layer of very soft to soft marine clay deposits, the uncontrolled end-tipped material has generated mud waves
and they were encroaching the piles supporting the Macau International Airport taxiway nearby. In order to prevent future potential
damage to the taxiway, the Macau Government engaged AECOM Asia Co. Ltd.(AACL), to design a containment bund adjacent to the
taxiway to retain the waste and to prevent further generation of mudwaves that would affect the taxiway. The sustainable design
prepared by AACL comprised the installation of vibrocompacted stone columns installed in over 20 m thick, very soft to firm,
moderately sensitive marine clay and alluvial clay,as the foundation to the waste retention bund, thereby avoiding the dredging and
off-site disposal of a significant volume of dredged sediments. This paper presents the design approach and construction of the stone
columns and the behaviour of the completed seawall.
RÉSUMÉ : La décharge de Cotai est la principale installation de réception de déchets de chantiers de construction à Macao. Comme
le site d'immersion repose sur une épaisse couche de dépôts d'argile marine très molle à molle, les matériaux en vrac ont généré des
écoulements de boue et ils interpénétraient les pieux soutenant les voies de circulation de l'aéroport international de Macao. Afin
d'éviter des dommages potentiels futurs à la voie de circulation, le gouvernement de Macao a engagé AECOM Asie Co. Ltd.(AACL),
pour concevoir une enceinte de confinement adjacente à la voie de circulation pour retenir les déchets et prévenir une nouvelle
génération de coulée de boue qui aurait une incidence sur la voie de circulation. La conception durable établie par AACL comprend
l'installation de colonnes ballastées installées dans des couches de plus de 20 m d’épaisseur, constituées d’argiles marines de
consistance très molles à ferme, moyennement sensibles et d’argile alluviale, comme la fondation de l’enceinte de rétention des
déchets. Ceci permet d'éviter le dragage et l'élimination hors du site d'un volume significatif de sédiments dragués. Cet article présente
l'approche de conception et la construction des colonnes ballastées ainsi que le comportement de l’enceinte terminée.
KEYWORDS : Soft Clay, Ground Treatment, Stone Column, Mudwaves, Seawall.
1 INTRODUCTION
In 2000s, Macau experiencing a major construction boom, the
site formation and building works for major casinos, roads and
infrastructure on reclaimed land as well as demolition of
existing structures generated a large volume of construction
waste. It comprised predominantly of spoil materials from
basements excavations and piling works.
Cotai Landfill is the main receiving facility in Macau for
building construction waste materials. Due to the rapid
development activities in late 2000s, the landfill material is
being generated at a much faster rate than initially anticipated.
In 2008, it was observed that dumping of the construction waste
have spread out as well as caused the underlying soft marine
mud to displace in the form of mudwaves towards the Macau
International Airport (MIA) Southern Taxiway Bridge (STB)
and the cooling water intake at the Coloane power plant located
in the vicinity of the Landfill (Figure 1).
Figure 1. View of the Landfill Site and Mudwaves
This paper present the work for the initial phase of the
protection measures against the mudwaves along the STB of
MIA. The purpose of the proposed works is to achieve the
following objectives:
a) prevent the propagating of mudwaves toward the MIA
to protect the STB;
b) maintain the operation of the landfill site as well as
maximise the capacity of the landfill site, and;
c) to facilitate the future development of the MIA
extension project.
Figure 2. Site Layout Plan
Taxiway
Runway
Seawall
Coloane Power
Station
Mudwave
Landfill
Cotai
Reclamation
Coloane
Taipa
Macau
international
Airport
Runway
Coloane Power Plant
Mudwaves
Landfill
Taxiway Bridge
