Dr. R. G. Robinson Department of Civil Engineering IIT Madras, India

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 40-50 years

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 Punggol Changi Airport Tekong/ Ubin Kranji Jurong Island Reclaimed area=31% Marina Bay Tuas Pasir Panjang Port Sentosa Southern Islands Strait Times (2000)

13. Land Reclamation in Singapore-Some major projects

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

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 Lumps placed in a barge Dredging of seabed

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

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: 900-1000 m3

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

40. Typical time-settlement curve Time, min 0.1 1 10 100 0 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 27 kPa 50 kPa 100 mm

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 Dsv=100 kPa Inside the lump In between the lumps Inside the lump In between the lumps 25-50 kPa