Construction of a Semi-Buried Building A Super-sized Shopping Mall : The Festival Walk

Transcription

1 Construction of a Semi-Buried Building A Super-sized Shopping Mall : The Festival Walk Presented by Raymond Wong Wai Man, Division of Building Science & Technology, City University of Hong Kong Raymond Wong 1

2 General Information Site area sq m (overall measure 290m x 80m) geological features - Tat Chee Avenue (+35m) on one longitudinal sides and the Kowloon Canton Railway (+20m) on the other, a level diff. of about 15m exist. - rockhead range between +25m to -35m. - Mass Transit Railway tunnels cutting across site at +8m - deepest basement down to -3m (36m below Tat Chee Av.) Raymond Wong 2

3 N Site 25m roadway (Tat Chee Avenue) Railway track Block Plan Raymond Wong 3

4 Building Section along Tat Chee Road Raymond Wong 4

5 Diaphragm Wall Raymond Wong 5

6 Typical Section cutting through MTR tunnels Raymond Wong 6

7 Site Formation and Diaphragm Wall Construction Sub-divided into 7 stages from level +35m down to +20m. Diaphragm wall and bored pile foundation construction work at the same time. Two rows of temporary ground anchor were installed at Diap. Wall along Tat Chee Avenue Av as lateral support to cut during site formation excavation. Raymond Wong 7

8 Boring Machine Temporary Ramp Diaphragm Wall Preliminary Site Formation Raymond Wong 8

9 Tat Chee Av Row of anchor as lateral retrain to diaphragm wall Raymond Wong 9

10 Tat Chee Av. Hand-dug caisson in progress (bored pile) KCR Rail track Site at the up-hill portion had been formed down to +20m (level to the KCR Rail track level) Raymond Wong 10

11 Site formation close to its completion Raymond Wong 11

12 Site Formation and Diaphragm (cont.) 2m thick Diap. Wall constructed using traditional grab/chisel and reverse circulation trench cutting (hydrofraise) methods, both using bentonite slurry as a stabilizing agent. Removal of soil maintained at 2 exit-points arrangement as far as possible Later stage of site formation merged with the main contract. Raymond Wong 12

13 Using a trench cutting machine (hydrofraise) to form the diaphragm wall panel Raymond Wong 13

14 Detail of the cutting drums of the hydrofraise (trench cutting machine) Raymond Wong 14

15 Forming the diaphragm wall panel using grabs (clamshell) Raymond Wong 15

16 Bored Pile Foundation Total about 165 piles ranging from 1.8, 2.65 and 3.25m dia. 3.25m dia piles were done by hand-dug method. Excavation done by steel grab/chisel and reverse circulation drilling method, both using steel casing as excavation support. With steel stanchion anchored into the pile as support to basement structure constructed in top-down arrangement. Raymond Wong 16

17 MTR Kwun Tong Line Tunnels Bored Piles Layout Raymond Wong 17

18 Forming the bored pile using grab Protective steel casing Raymond Wong 18

19 Forming the bored pile using Reversed Circulation Drill Raymond Wong 19

20 Stages of construction Raymond Wong 20

21 Stages of construction from site formation to completion of superstructure Excavation start at this point Diaphragm wall MTR Tunnels Ground anchor to serve as lateral support during excavation 2.5m dia bored pile Site formation stages Raymond Wong 21

22 Basement excavation below the ground slab Commencement of Top-down Basement Construction Upper floor slab and basement excavation and construction work at the same time Excavation to form the vehicular ramp Raymond Wong 22

23 Work Flow direction Completed vehicular ramp in advance to facilitate the removal of excavated spoil Superstructure Basement excavation and construction Raymond Wong 23

24 Atrium space Raymond Wong 24

25 Topping out of the entire structure Raymond Wong 25

26 Construction of Basement 4-level full basement and 3-level semi-basement. Full basement constructed in top-down method. Construction generally arranged in a 6-phased manner, each with appropriate sub-sectioning depending to local layout. Spoil removal: 1 st stage, maintain a exit point to road level on the down-slope side of site; 2 nd stage, use the newly constructed vehicle ramp (permanent structure) at the up-slope side. Raymond Wong 26

27 Steel stanchions to be inserted into bores piles as temporary support during the top-down construction of the basement structure (encased to become column later) Steel stanchions Raymond Wong 27

28 Anchor plate at head of stanchion Floor slab formwork for basement at +22m Connecting the stanchion to the basement slab Raymond Wong 28

29 Exit point Provision of temporary ramp to exit point at down-slopel location Raymond Wong 29

30 Basement underneath to be formed by top-down method Vehicular ramp leading to basement carpark used as temporary access for removal of spoil during site formation and basement excavation Raymond Wong 30

31 orming an entrance into e basement for carrying out of excavation Raymond Wong 31

32 Progressing stage of superstructure & basement construction (1) Raymond Wong 32

33 Progressing stage of superstructure & basement construction (2) Raymond Wong 33

34 Progressing stage of superstructure & basement construction (3) Raymond Wong 34

35 Progressing stage of superstructure & basement construction (4) Raymond Wong 35

36 Progressing stage of superstructure & basement construction (5) Raymond Wong 36

37 Principle of top-down method: Construct the ground slab first (in this case slab between full and semi-basement at +20m). Provide an entrance to the basement to facilitate downward excavation (between portion 2 & 3 at the first start). Excavate downward until the proceeding slab being cast. Repeat the excavation and basement slab casting horizontally and vertically until the entire basement finished. Cast/encase other vertical elements (staircase, ramps or columns) at time appropriate. Raymond Wong 37

38 Forming the first basement slab at +20m Raymond Wong 38

39 Steel columns erected in the bored pile helps to support the ground slab at the beginning of the topdown basement construction Raymond Wong 39

40 Upper basement slab already cast Formwork for the lower basement slab being erected Excavation in progress Excavation and casting the basement slab in a top-down manner Raymond Wong 40

41 Steel columns support the ground slab at the beginning stage Raymond Wong 41

42 Excavation along Tat Chee Avenue where rockhead located close to ground Raymond Wong 42

43 Rock cutting carried out under the steel shore Raymond Wong 43

44 The Main Structure Traditional timber panel formwork was used. Majority of structure in span ranging from 8.5m to 16m, some post-tensioned beams up to 35m and 48m. Strength of concrete in 40 (in-situ) and 45 (post-tensioned). Phasing and sectioning arrangement somewhat similar to basement construction, but more complicated due to the layout of the shopping mall. Raymond Wong 44

45 Portion 1 Portion 6 Portion 4 Portion 2 Portion 3 Portion 5 Construction of the superstructure in complicated phases Raymond Wong 45

46 Superstructure constructed using traditional manual timber formwork Raymond Wong 46

47 Construction of the superstructure at its final stage (observe the complicated sectioning arrangement of formwork) Raymond Wong 47

48 series Raymond Wong 48

49 Steel fixing for the superstructure structure Raymond Wong 49

50 48m span post-tensioned girder beams Office block Skating rink below Elevation along Tat Chee Avenue Raymond Wong 50

51 Main Structure : Other features - existence of large volume atrium spaces (120m x 35m high, 80m x 40) - ice skating ring measures 46m (span) x 70m x 30m high) - fully glazed sky light (180m x 22m for mall, 30m x 35m for office) - Glass wall total 3500 sq m. Raymond Wong 51

52 Isolated Island sub-divided by the River & canyon The River The canyon Complicated spacing arrangement within the superstructure Raymond Wong 52

53 Raymond Wong 53

54 The River taking shape Escalator spanning below two levels of the shopping mall Raymond Wong 54

55 Steel frame that formed the skeleton of the skylight of River and Canyon Intermediate frames Main frame Raymond Wong 55

56 Installing the glazing panels for the skylignt Raymond Wong 56

57 Office block Roof plan showing layout of River & Canyon Raymond Wong 57

58 Isometric view of the Festival Walk superstructure Raymond Wong 58

59 Glass wall that form the Canyon Raymond Wong 59

60 Forming the glass wall at end-side of Canyon Raymond Wong 60

61 Cladding the glass wall of the Canyon Raymond Wong 61

62 GI grille (A/C compressors behind Powder coated metal panels Marble slab Raymond Wong 62

63 Difficulties encountered in the project Very large scale of works site formation, volume of excavation, large layout, huge amount of formwork and concrete, interior space that fitting out works required etc. Very deep excavation and the required support. Works in close proximity with MTR facilities and tunnels. Difficult phasing and sectioning arrangement. Relatively tight schedule. Very high headroom and difficult accessible interior spaces sub-divided by the atrium. Raymond Wong 63

64 Complicated teething arrangement between interface of phased sections (1) Steel stanchion to support basement slab 1.2m thick slab (MTR tunnel tubes below) Raymond Wong 64

65 Complicated teething arrangement between interface of phased sections (2) Raymond Wong 65

66 Bored-piles as protection to pedestrian shaft Working close to the MTR pedestrian facilities in-situ bored piles were constructed to protect during excavation Raymond Wong 66

67 Steel strut supporting pedestrian shaft to partially completed basement structure Protecting the MTR pedestrian facilities Raymond Wong 67

68 MTR pedestrian and ventilation shaft Structural steel strut frame to stabilize the shaft Squeezing difficultly into the ground to form the basement structure when working close to the MTR facilities Raymond Wong 68

69 Diap. wall being concreted Cut into rockhead to extend diap. wall further downward Underpinning to extend diaphragm wall panels further down into the rockhead Raymond Wong 69

70 Vast volume within the atrium add difficulty in the carrying out of superstructure and interior works Raymond Wong 70

71 Finishing the atrium formed within the River Raymond Wong 71

72 The River and the skylight Raymond Wong 72

73 The 48m-span interior space at the skating rink and food-stall area Raymond Wong 73

74 Finishing the skating rink Raymond Wong 74

75 Finishing the 20m-high, 48m-span Skating Ring Raymond Wong 75

76 Construction of a series of linking bridge in structural steel within the atrium space of the Skating Rink Raymond Wong 76

77 The vast interior space within the long-span atrium area (skating rink) Raymond Wong 77

78 End of presentation Raymond Wong 78