SUMMARY OF RECENT CONSTRUCTION PROJECTS IN HONG KONG WITH THE INVOLVEMENT OF LARGE-SCALE BASEMENT, SEMI-BASEMENT OR OTHER UNDERGROUND STRUCTURE
Raymond Wong Wai Man, Division of Building Science and Technology, City University of Hong Kong
Commercial Developments and Institutional Buildings
1. East Point Centre Photo not available
Location:	Hennessy Road, Causeway Bay, Hong Kong.
Brief description and Features of the Project:	4-level basement, site area about 3,200 sq m. Tunnels of MTR Island Line laid within 5m distance to the basement boundary. Old foundations existed and required to be removed during excavation of the basement. Site situated in congested downtown area thus delivery of material and removal of spoil became very crucial factors.
Method of Basement Construction:	Sheet pile and diaphragm combination was used as cut-off and the basement was constructed using top-down method.
Approximate period of Works:	1993-1994
2. Pioneer Centre
Location:	Nathan Road, Mongkok, Kowloon.
Brief description and Features of the Project:	4-level basement, site area about 4,800 sq m. Tunnels of MTR Tsuen Wan Line laid within 5m distance to the basement boundary. Very stringent movement control was called for. Underpinning was also required for some of the diaphragm wall panels due to shallow-laying bedrock.
Method of Basement Construction:	Diaphragm wall was used as cut-off and the basement was constructed using top-down method.
Approximate period of Works:	1993-1994
3.  Lee Theatre Plaza
Location:	Percival Street, Causeway Bay, Hong Kong
Brief description and Features of the Project:	3-level basement, site area about 3,200 sq m. Typical congested site environment. Complicated temporary work platform was employed for positioning of plant and for spoil of spoil during basement excavation process.
Method of Basement Construction:	Sheet pile cofferdam was used with heavily strutted frame was use as lateral support and cut-off system. Basement structure was constructed using bottom-up method.
Approximate period of Works:	1994-1995
4.  Hollywood Plaza/Galaxia
Location:	Diamond Hill, Kowloon.
Brief description and Features of the Project:	6/3-level semi-basement/basement structure , site about 19,000 sq m. Step-terraced topography made access to site rather difficult. Part of the basement would later be broken through into the MTR Diamond Hill Station to form pedestrian entrance.
Method of Basement Construction:	In-situ bored pile on the higher side and sheet pile wall on the lower side were used as cut-off system for basement/semi-basement construction. Generally bottom-up method was employed for works.
Approximate period of Works:	1995-1997
5. Gateway I and II
Location:	Canton Road, Tsim Sha Tsui, Kowloon.
Brief description and Features of the Project:	4-level basement for Phase I and 2-level for Phase II, total site area about 22,000 sq m. Arrangement for the demolition of the old basement (in phase II) was to be made at the same time when constructing the new basement. Due to the close proximity to the seawall, uplifting caused by tidal effect was tremendous. Generations of old piles also existed in the site that increased the difficulty during the basement construction process
Method of Basement Construction:	Both phases employed diaphragm wall as the cut-off system. For Phase I, top-down method was used; while for Phase II, it used bottom up approach with the central core being constructed first and shored to support the diaphragm wall on the sides.
Approximate period of Works:	Ph I: 1994 - 1996 Ph II: 1997-1998
6. Hong Kong Industrial Technology Cetnre Photo not available
Location:	Tat Chee Avenue, Yau Yat Tsuen, Kowloon.
Brief description and Features of the Project:	3-level semi-basement on 4,600 sq m. step-terraced site. Basement structure was in close proximity to sensitive environment on three sides including the Tat Chee Avenue on one, the KCR track on the other, and the existing Hong Kong Productivity Centre on the northern side.
Method of Basement Construction:	Caisson wall lagged with in-situ RC panel was used as cut-off. Basement structure was constructed using bottom-up method.
Approximate period of Works:	1994-1995
7. Tsuen Wan Town Centre Photo not available
Location:	Chung On Street, Tsuen Wan.
Brief description and Features of the Project:	3-level basement, with site area about 3,800 sq m.
Method of Basement Construction:	Diaphragm wall was used as cut-off and basement constructed using top-down method.
Approximate period of Works:	1994 - 1995
8. The Harbour Front/Harbour Plaza Photo not available
Location:	Whampoa, Hung Hom, Kowloon.
Brief description and Features of the Project:	3-level basement, site area about 11,000 sq m. The control of ground water was a crucial factor during basement construction for the site was in close proximity to the seawall.
Method of Basement Construction:	Diaphragm wall was used as the cut-off. Top-down method was employed for basement construction.
Approximate period of Works:	1994 - 19965
9. Witness of the Christ Church
Location:	2, Cornwall Street, Kowloon Tong, Kowloon.
Brief description and Features of the Project:	3-level basement, site area about 2,300 sq m. Congested site with slopes and existing residential buildings in close proximity. Complicated lateral support and elevated platform were erected to facilitate works.
Method of Basement Construction:	Pipe-pile was used as cut-off wall. Basement constructed using bottom-up method.
Approximate period of Works:	1994 - 1995
10. Manual Lift Tower (Lee Garden Redevelopment)
Location:	Hysan Avenue, Causeway Bay, Hong Kong.
Brief description and Features of the Project:	4-level basement, site area about 5,700 sq m. The 2-level old basement was to be demolished and replaced by the new at the same time during construction. The foundation and structure of the core wall of the new building was carried out at the same time with the basement thus creating very complicated interfacing problems during construction.
Method of Basement Construction:	Hand-dug caisson was used as cut-off on the outer face of the old basement wall. New basement was constructed using top-down method with the provision of additional temporary shores during excavation.
Approximate period of Works:	1995 - 1997
11. Grand Millennium Plaza
Location:	Queen's Road/Wing Lok Street, Sheung Wan, Hong Kong.
Brief description and Features of the Project:	3-level basement in the main block and 2 in the annexed block, site area about 8,000 sq m. Structure of basement was basically divided into two separated and independent sections that confined the scale of the basement to easier manageable portions. The diaphragm wall panels would be broken through to form an entrance to the MTR Sheung Wan Station when the basement structure being completed.
Method of Basement Construction:	Diaphragm wall (the main block) and sheet pile cofferdam (annexed block) were used as cut-off system and the basement was constructed using bottom-up method.
Approximate period of Works:	1995-1996
12. The Center
Location:	Queen's Road Central, Hong Kong.
Brief description and Features of the Project:	3-level basement, site area about 9,500 sq m. Four 24m diameter shaft lined with diaphragm wall panels were used as part of the footing system for the four super-columns of the building in Mega-structure design. The diaphragm wall shaft would be removed when excavation proceeded down into the basement.
Method of Basement Construction:	Diaphragm wall and medium sized in-situ bore pile wall were used as cut-off. Basement was constructed using top-down method.
Approximate period of Works:	1995 - 1997
13. Festival Walk
Location:	Kowloon Tong, Kowloon.
Brief description and Features of the Project:	7/4-level basement, site area about 21,000 sq m. MTR Kwun Tong Line cut through the site, and with the KCR track and the pedestrian exit and ventilation shaft of MTR Kowloon Tong Station in close proximity. Underpinning to some of the diaphragm wall panels were required due to shallow-laying bedrock.
Method of Basement Construction:	Diaphragm wall was used as cut-off and basement constructed using top-down method. Basement sub-divided into 6 main phases during construction.
Approximate period of Works:	1995 - 1998
14. The Palace Mall Photo not available
Location:	Salisbury Road, Tsim Sha Tsui
Brief description and Features of the Project:	4-level underground shopping mall, site area about 5,500 sq m., within close proximity to Salisbury Road, MTR tunnels and seawall along Tsim Sha Tsui East Promenade. MTR tunnels and ventilation shaft also laid close to the basement boundary.
Method of Basement Construction:	Diaphragm wall was used as cut-off and underground structure constructed using top-down method.
Approximate period of Works:	1994 - 1996
15. North Point Government Office Building
Location:	Java Road, North Point, Hong Kong.
Brief description and Features of the Project:	1-level basement, site area about 4,400 sq m. Site situated within 5m of the seawall. Surrounding ground was heavily grouted as a means to stabilize subsoil and to control the entrance of ground water.
Method of Basement Construction:	Sheet pile and pipe-pile (due to existence of boulder) were used as cut-off system. Corner bracing and raking shore were used as lateral support. Basement was constructed using bottom-up method.
Approximate period of Works:	1996 - 1997
16. Academic Exchange Centre of City University of Hong Kong
Location:	Kowloon Tong, Kowloon.
Brief description and Features of the Project:	2-level semi-basement plus foundation raft was to be constructed, site coverage about 3,600 sq m. Site surrounded on two sides with gently sloping road, with an average level difference of about 8m from road surface to formation level.
Method of Basement Construction:	Pre-drilled soldier pile was used as excavation support. Anchor block was cast on foundation raft as constraint to raking shores.
Approximate period of Works:	1996-1997
17. Oxford Centre
Location:	Westland Road, Quarry Bay, Hong Kong.
Brief description and Features of the Project:	4-level basement, site area about 2,800 sq m. Geological background was mainly made-ground with abandon marine deposit, that made ground water and settlement control became crucial.
Method of Basement Construction:	Diaphragm wall as cut-off and basement construction using top-down method.
Approximate period of Works:	1997 - 1998
18. CEF Life Tower
Location:	Tai Yuen Street, Wanchai, Hong Kong.
Brief description and Features of the Project:	4.5m deep caisson cap as the main substructure. Very old buildings (some up to 40 years) were located around the site.
Method of Basement Construction:	Sheet pile cofferdam with raking shore as main soil support system. Sub- structure was constructed using bottom-up method.
Approximate period of Works:	1997
19. Cheung Kong Center
Location:	Queen's Road/Garden Raod, Central, Hong Kong.
Brief description and Features of the Project:	5-level basement, site area about 9,650 sq m. Gently sloped site with a 2-level old basement to be replaced during construction of the new one. A 37m diameter shaft lined with diaphragm wall panels was formed to facilitate the construction of the raft foundation of the building core. Complicated temporary ramp was formed for the removal of spoil from the excavated. An accelerated "Double bit" method was also employed by excavating two layers of basement at the same time and with the intermediate slab cast at a later stage.
Method of Basement Construction:	Diaphragm wall as cut-off system and basement constructed using top-down method.
Approximate period of Works:	1997 - 1998
20. Kwong On Bank Redevelopment
Location:	155, Queen's Road Central, Hong Kong.
Brief description and Features of the Project:	2-level basement, site area about 1,200 sq m. Very congested urban environment associated with problems such as special arrangement for transportation, work platforms, storage and other confined space provisions.
Method of Basement Construction:	Cofferdam as cut-off, heavily strutted, and basement constructed using bottom-up method.
Approximate period of Works:	1997 - 1998
21. Man Yee Building
Location:	Queen's Road/Pottinger Street, Central, Hong Kong.
Brief description and Features of the Project:	3-level basement, site area about 2,200 sq m. Gently sloping site in busy urban environment. Complicate work platform was erected for the placing of heavy crane during the basement excavation process. 800mm diameter tubular strut was used as lateral support.
Method of Basement Construction:	Diaphragm wall as cut-off on the Queen's Road and Pottinger Street sides, and sheet pile wall on the Des Voeux Road side. Basement constructed using bottom-up method.
Approximate period of Works:	1997-1998
22. International Finance Centre, Phase I
Location:	Central Reclamation, Central, Hong Kong.
Brief description and Features of the Project:	5-level underground structure, work coverage area about 2.600 sq m. A 55m-diameter shaft lined with 1.2m thick diaphragm wall was formed as the main underground structure which used as a pair of vehicular access into the underground carpark.
Method of Basement Construction:	Diaphragm wall as cut-off system and basement was constructed using bottom-up method.
Approximate period of Works:	1996 -1998
23. Olympia Plaza Photo not available
Location:	King's Road, North Point, Hong Kong.
Brief description and Features of the Project:	4-level basement, site area about 1,750 sq m. RC basement wall and internal walls were cast in-situ which acted also as load bearing elements to the superstructure.
Method of Basement Construction:	Pipe-pile wall as cut-off up to surface of rockhead. Onward excavation was formed by cutting into bedrock. Basement was then constructed using bottom-up approach.
Approximate period of Works:	1997-1998
24. Cheung Sha Wan Government Office Photo not available
Location:	Cheung Sha Wan Road, Sham Shui Po, Kowloon.
Brief description and Features of the Project:	3-level basement, site about 4,700 sq m. Tunnel of MTR Tsuen Wan Line located within 5m of basement. Grout curtain was introduced at the base of diaphragm wall as a means of ground water control aiming to minimize up-heaving and ground movement that might affect the stability of the MTR tunnels.
Method of Basement Construction:	Diaphragm wall as the cut-off system, basement was constructed using top-down method. Temporary raking shore was introduced as an addition lateral support during excavation.
Approximate period of Works:	1998 - 1999
25. North Point Hyatt Hotel
Location:	665, King's Road, North Point, Hong Kong.
Brief description and Features of the Project:	1-level basement, site about 3,000 sq m. Temporary storage and work platform was formed to facilitate basement excavation and construction due to the relatively congested site environment.
Method of Basement Construction:	Sheet pile cofferdam was used as cut-off and laterally supported by bracing, shore and strut system, basement constructed using bottom-up method.
Approximate period of Works:	1998 - 1999
Residential Developments
1. Hollywood Terrace
Location:	Queen,s Road/ Hollywood Road, Hong Kong.
Brief description and Features of the Project:	5-level semi-basement, site area about 4,600 sq m. Site span across the Queen's Road Central and the Hollywood Road with a level difference of about 25m. Site surround with aged building and very stringent requirements were applied for the control of the ground movement to the nearby environment.
Method of Basement Construction:	Hand-dug caisson with soldier pile on top being used as the cut-off system.
Approximate period of Works:	1995 - 1998* *work being temporary suspended due to uncontrollable ground movement
2. The Belcher's
Location:	Pokulam Raod/ Belcher's Street, Kennedy Town, Hong Kong.
Brief description and Features of the Project:	10-level semi-basement/site formation, site area about 16,000 sq m. Sub-soil consisted of large amount of solid granite making excavation very time consuming and difficult. Large area of semi-basement/podium structure required very careful phasing and sectioning arrangement during construction.
Method of Basement Construction:	Due to rocky nature of site, no specific cut-off retaining structure was required. Scattered buttress wall, rock bolt or rock anchor were installed as a means of ground/slope stabilization.
Approximate period of Works:	1998 - 2000
3. Royal Peninsula
Location:	Hung Hom South Road, Hung Hom Bay, Kowloon.
Brief description and Features of the Project:	2-level basement, site area about 4,800 sq m. Site located on newly reclaimed land. Construction of the basement had to be subdivided into complicated section due to large area and complex internal partition of the basement structure.
Method of Basement Construction:	Sheet pile wall was used as the cut-off with raking shore system, installed as stages, as lateral support. Bottom-up method was employed due to the shallowness of the basement.
Approximate period of Works:	1998 -1999
4. Majestic Park
Location:	Farm Road, Ma Tau Wai, Kowloon.
Brief description and Features of the Project:	3-level basement/semi-basement on a gently sloping site of about 4,600 sq m. in size.
Method of Basement Construction:	Hand-dug caisson, lagged with in-situ RC panels, was used as the cut-off. Basement was constructed using bottom-up method.
Approximate period of Works:	1997-1998
5. Emperor Height Photo not available
Location:	Cox Road, Jordan, Kowloon.
Brief description and Features of the Project:	3-level semi-basement, site area about 3,200 sq m. Since existing residential buildings were located in close proximity of site, complicated protection provision was to carry out during the construction of the semi-basement structure.
Method of Basement Construction:	1.2 m diameter Hand-dug Caisson as cut-off walling. Semi-basement structure was constructed using bottom up method.
Approximate period of Works:	1995 - 1996
6. Island Harbour-view
Location:	Olympic Station, Tai Kok Tsui, Kowloon.
Brief description and Features of the Project:	1-level basement used mainly as carpark, site coverage about 42,000 sq m. Difficulty in works mainly came from the vast size of the basement area resulted to very complicated phasing and sectioning arrangement in the basement planning process.
Method of Basement Construction:	Sheet pile with raking shore system installed in controlled phases to support excavation. Basement was constructed using bottom-up method.
Approximate period of Works:	1997 - 1998
Other Civil/Public Projects
1. Extension to MTR Kowloon Tong Station
Location:	Kowloon Tong, Kowloon.
Brief description and Features of the Project:	2-level pedestrian entrance shaft about 12m below ground level, work area about 1,100 sq m.
Method of Basement Construction:	Hand-dug caisson was used as cut-off to support excavation. Bottom-up method was employed for the work.
Approximate period of Works:	1994 - 1995
2. Extension to MTR Wanchai Station
Location:	Wanchai, Hong Kong.
Brief description and Features of the Project:	4-level underground structure used as pedestrian entrance shaft to the station. The approximately 3,300 sq m. site was located within very congested downtown environment with existing buildings, buried services and busy traffic around. Complicated services and traffic diversions were required at stages during the excavation process. Breaking through arrangement between old and new station structure was to be made at appropriate stages.
Method of Basement Construction:	Diaphragm wall was used as the cut-off. Shaft and entrances were constructed using bottom-up method.
Approximate period of Works:	1997 - 1998
3. Hong Kong Station, Airport Railway
Location:	Central Reclamation, Central, Hong Kong.
Brief description and Features of the Project:	5-level underground structure with a site coverage of about 65,000 sq m. Complicated spoil removal arrangement was to be provided due to the huge amount of excavated spoil. Careful ground movement control was required for its proximity to nearby sensitive high-rise buildings.
Method of Basement Construction:	Diaphragm wall was used as the cut-off. Underground station structure was constructed using top-down method and partly in "double bit" arrangement.
Approximate period of Works:	1995 - 1997
4. Kowloon Station, Airport Railway
Location:	Jarden, West Kowloon Reclamation, Kowloon.
Brief description and Features of the Project:	5-level underground structure with a site coverage of about 80,000 sq m. Large area of underground structure required very careful phasing and sectioning arrangement during construction.
Method of Basement Construction:	Diaphragm wall was used as cut-off in general. However, for the first two levels of structure, open-cut method was used, while for the remaining levels top-down method was employed in construction.
Approximate period of Works:	1995 - 1997
5. Central Pedestrian Subway, Hong Kong Station
Location:	Pedder Street/ Connaught Road, Central, Hong Kong.
Brief description and Features of the Project:	2-level subway system with the upper portion for pedestrian and the lower for services. Formation level at -20m below road level. It stretched about 600m running from the Central Station to the Hong Kong Station of the MTR under Pedder Street and Des Vouex Road. Very complicated diversions for buried services and ground traffic were carried out during the construction.
Method of Basement Construction:	In-situ bored-pile and soldier pile in various locations were used as cut-off system. Structure was constructed in bottom-up method in general.
Approximate period of Works:	1995 -1997
6. Ventilation Building, Hong Kong Station, Airport Railway
Location:	Central Reclamation, Hong Kong.
Brief description and Features of the Project:	4-level underground structure including tunnel tubes for the Airport Railway. Site coverage about 1,800 sq m., excavation was done in newly reclaimed land. Excavation/formation level down to 24m from ground.level (-18.5mPD).
Method of Basement Construction:	Diaphragm wall/Soldier pile combination as the cut-off system. Structure was basically constructed by top-down method.
Approximate period of Works:	1996 - 1997
7. Tiu Keng Leng Station, MTR Tseung Kwan O Extension
Location:	Tseung Kwan O
Brief description and Features of the Project:	4-level underground structure, site coverage about 15,000 sq m. Sub-soil was mainly composed of slightly decomposed granite. The forming of the working pit was thus very time consuming and expensive.
Method of Basement Construction:	No specific cut-off walling was required due to rocky geological condition. At certain location rock bolts were installed to stabilize some of the fractured surfaces. Bottom-up method was used for the construction.
Approximate period of Works:	1998 - 2001
8. Tseung Kwun O Station, MTR Tseung Kwan O Extension
Location:	Tseung Kwan O
Brief description and Features of the Project:	4-level underground structure, site coverage about 18,000 sq m. Station and the approach tunnels were located within a series of servicing roadway, thus temporary diversion to the traffic was required from time to time as the construction works proceeded.
Method of Basement Construction:	Diaphragm wall was employed as the cut-off. Bottom-up method was used for the construction except in certain locations (under servicing roadway), top-down concept was adopted.
Approximate period of Works:	1999 - 2002
9. Hang Hau Station, MTR Tseung Kwan O Extension
Location:	Tseung Kwan O
Brief description and Features of the Project:	2/4 level underground structure, site coverage about 34,000 sq m. Temporary diversion to the traffic was required from time to time as the construction works proceeded due to complicated connection of the station and approach tunnel structures which occupied part of the existing roadway.
Method of Basement Construction:	Soldier pile (station entrance) and diaphragm wall (station structure) were being used as cut-off. Bottom-up and top-down combination was adopted to maximize the efficacy of work due to differences in excavation depth.
Approximate period of Works:	1999 - 2002
10. Mei Foo Station, KCR West Rail
Location:	Mei Foo, Kowloon.
Brief description and Features of the Project:	2-level underground structure with a series of approach tunnels, site coverage about 39,000 sq m. Diversion works both to vehicular and pedestrian traffic were required at appropriate stages during construction.
Method of Basement Construction:	Part of the structure was done by open-cut method (south portion) and partly using sheet pile cofferdam as the cut-off system.
Approximate period of Works:	1999 - 2002
11. Tsuen Wan West Station, KCR West Rail
Location:	Tsuen Wan Reclamation, Tsuen Wan
Brief description and Features of the Project:	3 level underground structure, site coverage about 62,000 sq m. Since the site was located in newly reclaimed land, associated works such as diversion of storm water culvert, drainages as well as to the existing surface traffic were thus involved. This caused serious interruption to the excavation and construction work and very tedious planning coordination were thus called for.
Method of Basement Construction:	In general, soldier pile and diaphragm wall was used as cut-off. Bottom-up method was adopted for the underground station construction.
Approximate period of Works:	1999 - 2002