1. GEOTECHNICAL ENGINEERING ECG 503 LECTURE NOTE 12
4.0 GROUND IMPROVEMENT TECHNIQUES

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. Hydraulic Methods and Objective of Vertical Drain and Preloading
TOPIC TO BE COVERED
Mechanical Methods and Objective; Stone Column, Dynamic Compaction, Vibrofloatation and Vibro Compaction.
Physical and Chemical Methods and objective; Grouting and cement column
Hydraulic Methods and Objective of Vertical Drain and Preloading

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

15. Smooth-wheeled Roller

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

17. Sheepsfoot Roller to Compact Clay Soils

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

19. Impact Roller to Compact the Ground

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

28. 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)

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

34. 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)

35. Vibroflotation

36. Vibroflotation

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

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

45. Grader for spreading soil

46. Bulldozer for spreading soil evenly

47. Loader

48. Backhoe

49. Crawler mounted Hydraulic Excavator

50. Rock Breaker

51. 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

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

53. GENERAL BACKGROUND OF SOFT CLAY
Malaysia Coastal Area – Not fully developed
Soft clay usually located around the coastal area

54. The soft clay have been a source of difficulties for many years
The soft clay have been a source of difficulties for many years. The soft soil can cause settlement which can give a lot of problem and damage in several way. This is the reason why Malaysia’s coastal areas are not generally developed

55. TWO DISTINCT ATOMIC STRUCTURAL UNITS
0.29 nm
aluminium or magnesium
hydroxyl or oxygen
oxygen
silicon
0.26 nm
Silicon Tetrahedron
Aluminium Octahedron

56. Micro-fabric particles in natural clay.
Dispersed
Flocculated

57. Flaky shape
Plate like structure

58. ION EXCHANGE

59. Ground Improvements for Soft Clay
Stone Column (Vibro-Replacement)
Prefabricated Vertical Drain
Cement Column

60. VIBRO-REPLACEMENT (STONE COLUMN)

62. Vibro-Replacement
Also known as stone column. The technique are similar to vibroflotation/vibrocompaction except the granular fill materials which used is sand is replaced by gravel stone sizes ranging from 50mm to 100mm

63. Soil Layer
Increase in density
Increase in bearing capacity
Radial drainage (help to improve settlement)
Shear strength of soil improve
Reinforcing the soil by applying rigid member (stone column) inside the soil

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

68. PREFABRICATED VERTICAL DRAIN (PVD)

74. CEMENT COLUMN (CHEMICAL STABILIZATION)

76. APPLICATION OF STABILIZE CLAY

90. GROUTING TECHNIQUE

100. EXAMPLE OF CASE STUDY FOR GROUND IMPROVEMENT METHODS ON SOFT CLAY

101. GEOTEXTILES