1. GEOTECHNICAL ENGINEERING ECG 503 LECTURE NOTE 11 TOPIC : 4
GEOTECHNICAL ENGINEERING ECG 503 LECTURE NOTE 11 TOPIC : 4.0 GROUND IMPROVEMENT TECHNIQUES MARCH 2009

2. LEARNING OUTCOMES Learning outcomes:
At the end of this lecture/week the students would be able to:
Understand natural slope and made engineered soil slope assessment which include rainfall induced failure and role of suction.

3. Objective and Principles of Ground Improvements
TOPIC TO BE COVERED
Objective and Principles of Ground Improvements
Types of Ground Improvements With Respect of Cohesionless and Cohesive Soil
Mechanical Methods and Objective; Stone Column, Dynamic Compaction, Vibrofloatation and Vibro Compaction.

15. Vibrating Plates for compacting very small areas
effective for granular soils

16. Smooth-wheeled Roller

17. Smooth Wheeled Roller
Compacts effectively only to mm; therefore, place the soil in shallow layers (lifts)

18. Sheepsfoot Roller to Compact Clay Soils

19. Sheepsfoot Roller
Provides kneading action; “walks out” after compaction
Very effective on clays

20. Impact Roller to Compact the Ground

21. Impact Roller
Provides deeper (2-3m) compaction. e.g., air field

29. Dynamic Compaction - pounding the ground by a heavy weight
Suitable for granular soils, land fills and karst terrain with sink holes.
solution cavities in limestone
Pounder (Tamper)
Crater created by the impact
(to be backfilled)

33. Pounder (Tamper) Mass = 5-30 tonne Drop = 10-30 m

36. Vibroflotation Suitable for granular soils Practiced in several forms:
vibro–compaction
stone columns
vibro-replacement
Vibroflot (vibrating unit) Length = 2 – 3 m Diameter = 0.3 – 0.5 m Mass = 2 tonnes
(lowered into the ground and vibrated)

37. Vibroflotation

41. Vibroflotation

45. Stone Columns vibrator makes a hole in the weak ground hole backfilled
..and compacted
Densely compacted stone column

46. Blasting For densifying granular soils Aftermath of blasting
Fireworks?

47. Earthmoving Equipment
This is an Australian excavator, with height of a 3-storey building
Large Excavator (see minivan on left for scale)

48. Grader for spreading soil

49. Bulldozer for spreading soil evenly

50. Loader

51. Backhoe

52. Crawler mounted Hydraulic Excavator

53. Rock Breaker

54. Filed Compaction Smooth-wheel roller Vibratory roller
Different types of rollers (clockwise from right):
Smooth-wheel roller
Vibratory roller
Pneumatic rubber tired roller
Sheepsfoot roller

55. Big weights dropped from 25 m, compacting the ground.
Craters formed in compaction

56. GEOTEXTILES