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Site Characterization for the HZM Immersed Tunnel
Caractérisation du site pour le tunnel immergé HZM
Steenfelt J.S., Yding S., Rosborg A.
COWI, Copenhagen, Denmark
Hansen J.G.
Ben C. Gerwick, COWI Group Company, Oakland, USA
Yu R.
COWI China, Beijing, Peoples Republic of China
ABSTRACT: The 36 km long HZM Link, crossing the Pearl River estuary between Hong Kong in the east and Macao and Zhuhai in
the west is rated one of the most important current infrastructure projects in China. It is slated for completion in 2016 and consists of a
world record length of 6 km immersed tunnel, two artificial transition islands and some 30 km bridges with a dual three lane motor-
way. In order to provide the structural designers with the requisite input for proper soil structure interaction analysis a very extensive
site characterisation was carried out comprising geotechnical boreholes, CPTUs and seismic testing with associated advanced labora-
tory testing. This paper describes the results and calibration of geotechnical boreholes, CPTUs and advanced laboratory tests to pro-
vide the requisite tool for inference of ground stratification and stiffness variation to be used in the structural modelling of the im-
mersed tunnel, the design of piles and dredging slopes.
RÉSUMÉ : La liaison HZM de 36 km de long qui traverse l’estuaire du fleuve Pearl entre Hong-Kong à l’est, Macao et Zhuhai à
l’ouest, est considéré comme étant l’un des plus importants projets d’infrastructure en Chine. Le projet qui doit être achevé en 2016
est composé d’un tunnel immergé d’une longueur record de 6 km, de deux îles artificielles de transition et d’environ 30 km de pont
autoroutier à deux fois trois voies. Afin d’obtenir les éléments essentiels pour l’analyses de l’interaction entre les fondations et les
structures, une campagne de sondages géotechniques très détaillée a été menée comprenant des forages, des tests de pénétration au
cône (CPTU) et des sondages sismiques ainsi que les études en laboratoire correspondantes. Cet article décrit les résultats obtenus et
méthodes de calibration des forages, CPTU et des essais en laboratoire mis en œuvre afin d’obtenir les éléments de base nécessaire
pour la détermination des caractéristiques mécaniques des sols à utiliser pour la modélisation des éléments du tunnel immergé, la dé-
finition des pieux de fondation et l’étude des pentes de dragage.
KEYWORDS: Site characterization, immersed tunnel, CPTU, triaxial testing, undrained shear strength, settlements, spring stiffness.
1 INTRODUCTION
The Hong Kong-Zhuhai-Macao (HZM) Link crosses the Pearl
River Estuary in south-eastern China in the Guangdong prov-
ince connecting Hong Kong at Shek Wan, Lantau Island to the
Pearl at Macau and to the district of Gongbei, Zhuhai in
mainland China, see Figure 1.
Figure 1. Location of the HZM project in south-eastern China.
The link is 36 km in total length of which 6 km comprises the
immersed tunnel. The remainder consists of two artificial tran-
sition islands and low bridges some 30 km in total length.
The whole connection has the capacity of a dual three lane
highway.
Provisions for two possible future 570 m wide navigation
channels are planned along the immersed tunnel alignment with
proposed design dredging levels some 15-20 m below existing
seabed level.
The particular challenges for the design of the immersed
tunnel are:
the presence of very soft clays requiring extensive
dredging profiles and soil improvement,
very deep foundation level of the tunnel in order to al-
low for future navigation channels 570 m wide over
the central part of the tunnel,
up to 23 m sedimentation load over the central part of
the tunnel,
potential of differential settlements due to the highly
varying loading and ground stiffness conditions,
the need for mixed foundation solutions with end bear-
ing or settlement reducing piles near the artificial is-
lands and direct foundation for the central part.
In order to provide the structural designers with the requisite
input for proper soil structure interaction analysis for Detailed
Design, a very extensive site characterisation was required. The
scope and findings of this site characterisation are described in
this paper.
The Project Owner is the HZM Bridge Authority, and the de-
sign and construction is being undertaken by a Joint Venture
headed by the contractor China Communications and Construc-
tion Company (CCCC) Ltd.
