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Lumpy fill in land reclamation

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Presentation on theme: "Lumpy fill in land reclamation"— Presentation transcript:

1 Lumpy fill in land reclamation
Dr. R. G. Robinson Department of Civil Engineering IIT Madras, India

2 Prof. Tan Thiam Soon

3 Dr. Ganeswara Rao Dasari

4 Contents of Presentation
Overview Coastal Reclamation Lumpy fill Laboratory studies on lumpy fill Field Tests Conclusions

5 Contents of Presentation
Overview Coastal reclamation Lumpy fill Laboratory studies on lumpy fill Field tests Conclusions

6 Original land area : 580 km2 Population: 4 million Expected to increase to 5.5 million in years

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8 Contents of Presentation
Overview Coastal reclamation Lumpy fill Laboratory studies on lumpy fill Field tests Conclusions

9 Stages of Reclamation Stage I- Planning Identify the area to be reclaimed. (HDB, JTC and PSA are the major agencies). Stage II-Environmental Impact Assessment Tidal flow patterns, water level, sedimentation and water quality. Impact on sea life. Erosion of main land and silting of ports. Convince and get approval from Parliament.

10 ….. Stages of Reclamation
Stage III- Construction of sand bunds along the perimeter to contain the fill Stage IV-Placing of fill within the sand bund Sand Clay Hydraulic fill Lumpy fill Stage V-Soil stabilization Dynamic compaction if it is sand fill Surcharge if it is clay

11 Land Area Population density

12 Land Reclamation in Singapore-Growing city state
Southern Islands Sentosa Pasir Panjang Port Tuas Jurong Island Punggol Marina Bay Tekong/ Ubin Changi Airport Reclaimed area=31% Kranji Strait Times (2000)

13 Land Reclamation in Singapore-Some major projects
Year Site Area (ha) Vol. of sand, Mm3 Changi airport 750 40 Changi north 181 12 Tuas 637 69 Pulau Tekong Besar 510 28 Changi East 2086 272

14 Use the Unwanted Soil as Fill Material
Reclamation depth increasing Increasing Underground Constructions Use the Unwanted Soil as Fill Material In-land materials depleted Maintenance of Navigation Channels High cost of imported sand Lack of disposal ground

15 HYDRAULIC FILL- Clay slurry
Contains mainly slurry with occasional occurrence of small lumps suspended in slurry Apply surcharge to consolidate Double handling Cannot handle unwanted soil directly

16 Layered sand-clay scheme (Karunaratne et al. 1990)
Changi south bay Clay slurry 40 ha (1988) Trial project Clay slurry  200% water content after 1 week Sand cap can be formed for dosage < 15 cm Careful construction control crucial to prevent sand loss Sand placement rather time-consuming Cannot handle waste soils directly Clay slurry Clay slurry Seabed

17 Contents of Presentation
Overview Coastal reclamation Lumpy fill Laboratory studies on lumpy fill Field tests Conclusions

18 CLAY LUMPS Produced by underground construction & seabed dredging
Volume of lumps can easily exceed 1 m3 Waste soil (unwanted soil) can be handled directly 1.0m Clamb-shell grab Dredging of seabed Lumps placed in a barge

19 Lumpy Fill - Place the material in the form of lumps, directly at the reclamation site Dredging of seabed Clamshell grab

20 Clay lumps placed in a barge

21 Dumping of clay lumps by bottom-open barge
Barge size: Width: ~10 m Length: ~20 m Depth : ~5 m Volume: m3

22 Typical Land Reclamation Scheme
Sand surcharge Clay lumps Inter-lump voids Filled water Mean sea level Seabed

23 Some aspects…. Consolidation behaviour Closing of inter-lump voids
Shear strength of the fill after stabilization Creep/Secondary compression Influence of clay slurry in the inter-lump voids Effect of degree of swelling

24 Contents of Presentation
Overview Coastal reclamation Lumpy fill Laboratory studies on lumpy fill Field tests Conclusions

25 Typical seabed profile
After dredging Forms slurry ~8200 years Forms lumps ~24000 years May or may not form lumps Forms lumps ~28000 years

26 Soil used for the study Depth : 13m LL=77% PL=36% PI=41% Sand=5%
Silt size=55% Clay=40% NMC=60% 1.5 m

27 One-dimensional consolidation tests

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40 Typical time-settlement curve
Time, min 0.1 1 10 100 Cv=1.25 x 10-3 cm2/s H = 19 mm Double drainage 0.2 0.4 0.6 0.8 Settlement, mm 1 1.2 1.4 1.6 1.8

41 e-log sv’ curves from conventional oedometer tests on homogeneous clay
s’c=200 kPa OCR= 2.5

42 Tests on lumpy fill

43 Preparation of clay lumps
Cut using wire cutter 25 mm cubical lumps

44 Experimental set-up LVDT Burette Loading frame Perforated loading cap
Geotextile filter Clay lumps Geotextile filter Sand drain

45 Experimental Programme
1. Effect of packing (using 25 mm lumps) Placed directly in water-Test 1 Packed in the container and then added water (Test 2 and Test 3) 2. Effect of size 12.5, 25, 50 mm cubical lumps 3. Effect of degree of swelling Degree of swelling =0% 50% and 100%

46 State of the fill under different consolidation pressures in Test 1
0 kPa 10 kPa 100 mm 27 kPa 50 kPa

47 Effect of initial packing on e-logs’v curves
25 mm cubical lumps

48 Effect of size on e-logs’v curves
eiv = 0.60±0.03

49 Typical time-settlement curves

50 Pore pressure inside and in between the lumps
Dsv=25 kPa Inside the lump In between the lumps Dsv=100 kPa Inside the lump In between the lumps 25-50 kPa

51 Typical e-log sv’ curves of lumpy fill
Lump size : 25 mm No. of lumps: 90 Fill height: 170 mm 1.0 1.5 2.0 2.5 3.0 3.5 1 10 100 1000 Consolidation pressure, kPa Void ratio, e Lumpy fill Undisturbed ICL e0 = 1.59 s’c=200 kPa

52 Permeability of lumpy fill system
Lump size : 25 mm No. of lumps: 90 Fill height: 170 mm

53 Cone penetration test on lumpy fill
The Cone Lump size : 50 mm Penetration rate: 5mm/s 10 mm su Undrained shear strength svo Overburden pressure Nk Cone factor Nk = 9.5 against vane shear CPT were conducted under sv’=50, 100, 200 and 360 kPa 3 mm 30 mm Load Cell Thanks to Hokuto Ricken Co., Japan

54 Shear strength profile under 50 kPa

55 Shear strength profile under 100 kPa

56 Shear strength profile under 200 kPa

57 Shear strength profile under 360 kPa

58 Secondary compression of lumpy fill
Coeff. of Secondary Compression Mesri’s (Ca/Cc ) concept

59 Influence of clay slurry

60 Inter-lump voids filled with water Inter-lump voids filled with slurry
Clay slurry Lump Lump Water Lump

61 Experimental set-up LVDT Burette Loading frame Perforated loading cap
Geotextile filter Clay lumps Geotextile filter Sand drain

62 Typical time-compression curves

63 …….Typical time-compression curves……….

64 …….Typical time-compression curves

65 Applicability of Terzaghi’s theory

66 e-log s’v curves

67 Variation of permeability with consolidation pressure

68 Pore pressure inside and in between the lumps
Inter-lump voids with water Inter-lump voids filled with slurry Dsv=25 kPa Dsv=25 kPa Inside the lump Inside the lump In between the lumps In between the lumps 25-50 kPa

69 Pore pressure inside and in between the lumps
Inter-lump voids with water Inter-lump voids filled with slurry Dsv=100 kPa Dsv=100 kPa Inside the lump In between the lumps

70 Influence of swelling of lumps
Lumps in the field are very large and may not reach fully swollen state if sufficient time is not allowed before the application of surcharge Swelling test To find the time required for different degrees of swelling Degree of Swelling, Us w = moisture content of the specimens after immersing in water at any instant of time wi = initial moisture content of the specimen wf = moisture content of the fully swollen specimen Us Time For a cubical lump of 25 mm, t50=20 min

71 State of the lumpy fill under sv’ = 50 kPa (25 mm lumps)
Us = 0% Us=50% Us=100%

72 Swelling of clay lumps

73 THREE DIMENSIONAL SWELLING OF CLAY LUMPS
Method I Obtain the water content of the lump with time during swelling. Suitable for small size lumps only Method II Obtain the volume change with time during swelling Not simple for three-dimensional swelling Method III Obtain the pore-pressure dissipation with time Simple and easy to make the measurements

74 Three dimensional swelling of clay lumps
Soils used Kaolinite: LL=82%, PL=40% Cylindrical samples of 105, 205 and 400 mm Marine clay: LL=56%, PL=33% 105 and 205 mm PPT Tensiometer 28 mm 12 mm Instrument used 6 mm diameter

75 Performance of PPT in comparison with Tensiometer during desiccation
240 mm T PPT 240 mm

76 EXPERIMENTAL PROCEDURE
Load Split mould Water Outer container Lump Filter

77 Schematic of the split mould for conducting swelling test

78 View of the split mould for conducting swelling test
Pneumatic piston Split mould Outer container

79 View of the kaolinite lump of 400 mm diameter
after removing the split mould 400 mm

80 Dissipation of suction on submerging the kaolinite lump
of 400 mm diameter in water

81 Normalized suction at the centre of marine clay lumps

82 Initial state End state Kaolinite Marine clay

83 Variation of water content within the marine clay lump of
205 mm diameter after full swelling wl wo

84 Water content variation within the lump-Undisturbed
Cube : 50 mm wL wo

85 Finite Element Analysis

86 Finite Element Analysis
Finite Element mesh

87 Soil Parameters Property Kaolinite Marine clay f’o 25 23 Ko 0.58 0.61 n 0.3 E in kPa 3000 4000 k 0.05 0.03 kv in m/s e=1.21log(kv)+11.2 e=0.912 log(kv)+9.8 kh/kv 1.9 2.3

88 Effect of soil model (Kaolinite lump 105 mm diameter)
Acknowledgement: Dr. Ganeswara Rao Dasari (1) Linear Elastic 1 10 100 1000 10000 T i m e , s 0.2 0.4 0.6 0.8 1.2 N o r a l z d p u NLE2 (4) NLE1 LE (2) Non-linear Elastic (NLE1) (3) Non-linear Elastic (NLE2) k = log (OCR) (4) NLE2 -Permeability increased

89 Predicted and measured suctions at the centre of marine clay lumps

90 Big Tank Experiment 1.4m 1.5m

91 SAMPLE PREPARATION DREDGED & PLACED IN A FLAT BARGE
PACKED IN BAGS & TRANSPORTED TO THE LAB STORED IN CONTAINERS AFTER COVERING WITH CLING-FILM CUT TO CUBICAL LUMPS OF 150 MM

92 Size of lumps : 15 cm No. of lumps : 223 No. of layers : 6 Total weight : 1.37t Height of fill : 93 cm

93 Contents of Presentation
Overview Coastal reclamation Lumpy fill Laboratory studies on lumpy fill Field tests Conclusions

94

95 NUCLEAR DENSITY CONE ND-CPT
Density is related to scattering of gamma ray Cesium source Cs137 with half life of 37.6 years Housed in standard CPT: Diameter = 35.6 mm Cone angle = 60 Cone area = 10 cm2 Penetration = 1.5 cm/sec 30 cm Diameter

96 Calibration Curve Density Count Ratio (Rp) = [RI Count – BG Count ] / Standard Count

97 LUMPY FILL TEST SITE AT PULAU PUNGGOL TIMOR
Reclaimed  14 years ago 8 m dredged fill & 10 m sand fill

98 Test Plan Very dense grid: 79 ND-CPT 5 CPTS 11 Boreholes
Spacing 0.5 m at centre to 6 m at periphery 22 m 25.5 m

99 Final density of lumpy fill

100 Final shear strength of lumpy fill
Cone Penetration Test UU Test 0.23 s’v

101 Oedometer test results
OCR=2 OCR=1

102 Contents of Presentation
Overview Coastal reclamation Lumpy fill Laboratory studies on lumpy fill Field tests Conclusions

103 SOME ISSUES Time-settlement of lumpy fill Swelling of clay lumps
Double porous Heterogeneous initial condition Pore pressure generation and dissipation Swelling of clay lumps Time-swell End state

104 Acknowledgements NSTB and HDB for funding
Toa Corporation : Contractors for reclamation Kiso-Jiban : Contractors for in-situ Testing Researchers: Mr. M. Karthikeyan Research Engineer Mr. Yang Li-Ang Research Engineer Mr. A Vijayakumar Research Scholar Ms. Goh Wen Jean FYP Ms. Lim Chea Rong FYP Ms. Lim Hsiao Chern FYP Mr. Lim Chee Kiong FYP

105 Had Useful discussions with:
Dr. D. W. Hight Geotechnical Consulting Group, London, UK Prof. J. Locat Laval University, Canada Dr. H. Tanaka Port and Airport Research Institute, Japan Prof. M. Mimura Kyoto University, Japan Mr. M. Nobuyama Soil and Rock Engg. Co. Ltd., Japan Prof. J .Takemura Tokyo Institute of Technology, Japan

106 Thank you


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