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1 Compaction N. Sivakugan Duration = 10 minutes. SIVA Copyright©2001 2 What is compaction? A simple ground improvement technique, where the soil is densified.

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Presentation on theme: "1 Compaction N. Sivakugan Duration = 10 minutes. SIVA Copyright©2001 2 What is compaction? A simple ground improvement technique, where the soil is densified."— Presentation transcript:

1 1 Compaction N. Sivakugan Duration = 10 minutes

2 SIVA Copyright© What is compaction? A simple ground improvement technique, where the soil is densified through external compactive effort. + water = Compactive effort

3 SIVA Copyright© Compaction Curve Water content Dry density (  d ) optimum water content  d, max Soil grains densely packed - good strength and stiffness - low permeability

4 SIVA Copyright© Compaction Curve What happens to the relative quantities of the three phases with addition of water? Water content Dry density (  d ) soil water air difficult to expel all air lowest void ratio and highest dry density at optimum w

5 SIVA Copyright© Zero Air Void Curve All compaction points should lie to the left of ZAV curve - corresponds to 100% saturation Water content Dry density (  d ) Zero air void curve (S=100%) S<100% S>100% (impossible)

6 SIVA Copyright© Effect of Compactive Effort Increasing compactive effort results in: E1E1 E 2 (>E 1 )  Lower optimum water content  Higher maximum dry density  Lower optimum water content  Higher maximum dry density Water content Dry density (  d )

7 SIVA Copyright© Compaction and Clay Fabric Higher water content or higher compactive effort gives more dispersed fabric. more dispersed fabric Water content Dry density (  d )

8 SIVA Copyright© Line of Optimum Water content Dry density (  d ) Compaction curves for different efforts Line of optimum

9 SIVA Copyright©2001 Filed Compaction  Pneumatic rubber tired roller Different types of rollers (clockwise from right):  Vibratory roller  Smooth-wheel roller  Sheepsfoot roller

10 SIVA Copyright© Field Compaction Compacts effectively only to mm; therefore, place the soil in shallow layers (lifts) Smooth Wheeled Roller

11 SIVA Copyright© Field Compaction  for compacting very small areas Vibrating Plates  effective for granular soils

12 SIVA Copyright© Field Compaction  Provides kneading action; “walks out” after compaction Sheepsfoot Roller  Very effective on clays

13 SIVA Copyright© Field Compaction  Provides deeper (2-3m) compaction. e.g., air field Impact Roller

14 SIVA Copyright© Compaction Control -a systematic exercise where you check at regular intervals whether the compaction was done to specifications. e.g., 1 test per 1000 m 3 of compacted soil Minimum dry density Range of water content Field measurements (of  d ) obtained using sand cone nuclear density meter

15 SIVA Copyright© Laboratory Compaction Test - to obtain the compaction curve and define the optimum water content and maximum dry density for a specific compactive effort. hammer Standard Proctor: Modified Proctor: 3 layers 25 blows per layer 5 layers 25 blows per layer 2.7 kg hammer 300 mm drop 4.9 kg hammer 450 mm drop 1000 ml compaction mould

16 SIVA Copyright© Compaction Control Test compacted ground  d,field = ? w field = ? Compaction specifications Compare! w dd

17 SIVA Copyright©2001 Dynamic Compaction - pounding the ground by a heavy weight Suitable for granular soils, land fills and karst terrain with sink holes. Crater created by the impact Pounder (Tamper) solution cavities in limestone (to be backfilled)

18 SIVA Copyright©2001 Dynamic Compaction Pounder (Tamper) Mass = 5-30 tonne Drop = m

19 SIVA Copyright©2001 Dynamic Compaction

20 SIVA Copyright©2001 Vibroflotation Vibroflot (vibrating unit) Length = 2 – 3 m Diameter = 0.3 – 0.5 m Mass = 2 tonnes Practiced in several forms:  vibro–compaction  stone columns  vibro-replacement Suitable for granular soils (lowered into the ground and vibrated)

21 SIVA Copyright©2001 Vibroflotation

22 SIVA Copyright©2001 Vibroflotation

23 SIVA Copyright©2001 Vibroflotation

24 SIVA Copyright©2001 Vibroflotation

25 SIVA Copyright©2001 Vibroflotation

26 SIVA Copyright©2001 Vibroflotation

27 SIVA Copyright© Stone Columns vibrator makes a hole in the weak ground hole backfilled..and compacted Densely compacted stone column

28 SIVA Copyright© Blasting Aftermath of blasting Fireworks? For densifying granular soils

29 SIVA Copyright© Earthmoving Equipment Large Excavator (see minivan on left for scale) David and Goliath?

30 SIVA Copyright© Earthmoving Equipment Grader for spreading soil

31 SIVA Copyright© Earthmoving Equipment Bulldozer for spreading soil evenly

32 SIVA Copyright© Earthmoving Equipment Loader

33 SIVA Copyright© Earthmoving Equipment Backhoe

34 SIVA Copyright© Earthmoving Equipment Crawler mounted Hydraulic Excavator

35 SIVA Copyright© Earthmoving Equipment Rock Breaker


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