1. Educational Resource Library
Vibro Compaction
Vibro Compaction, also known as VibroflotationTM, is used to densify clean, cohesionless soils. The action of the vibrator, usually accompanied by water jetting, reduces the inter-granular forces between the soil particles, allowing them to move into a denser configuration, typically achieving a relative density of 70 to 85 percent. Compaction is achieved above and below the water table.
© HBI,

2. Vibro Compaction Process

3. Vibro Compaction Profile of Sand Grains
Volume reduction due to densification of non-cohesive soils may result in surface settlement of 5% to 15% of the treated depth.

4. Vibro Compaction Design Considerations
The design approach for Vibro technologies will generally be governed by one or more of the three major categories of site improvement:
Shear resistance increase
Settlement control
Liquefaction & lateral spreading mitigation

5. Vibro Compaction Range of Treatable Soils

6. Vibro Compaction Design Requirements
Design of the Vibro program requires information on:
Total loads (structure, surcharge, live, wind and seismic)
Soil type (variation, stratigraphy, groundwater location)
Type of footing/slab design
Structural settlement tolerance
Site restrictions and limitations
To address the above issues, the Vibro program is designed such that the zone of influence of the vibratory probe ensures the necessary soil densification and/or reinforcement.

7. Vibro Compaction Densification Results

8. Vibro Compaction Expected Results

9. Vibro Compaction Design Steps
1. Perform site investigation
Soil gradation important
2. Calculate performance with existing soil conditions
Problem understood
3. Establish compaction requirements
Sufficient densification to reduce settlement and/or prevent liquefaction
4. Develop appropriate Vibro Compaction approach
Treat entire site or just footing?
5. Establish testing criteria
Relative density, SPT, CPT, PMT, etc.

10. Vibro Compaction Increased Bearing Capacity
Bearing capacity is a function of the soil’s shear strength which is derived from the soil’s angle of internal friction (f) and/or cohesion (c). The Vibro systems increase the allowable bearing capacity by increasing the effective f angle.
Vibro Compaction densifies cohesionless granular soils, thus increasing the angle of internal friction directly. The allowable bearing capacity is calculated with conventional procedures using the improved angle.

11. Vibro Compaction Reduced Settlement
Settlement is a function of the soil’s modulus and consolidation character. Vibro systems decrease the settlement that will occur beneath a proposed foundation by either directly increasing the in situ soil’s modulus value and/or by constructing high modulus Vibro stone columns in a grid pattern beneath the planned foundation.
Vibro Compaction densifies cohesionless granular soils, thus increasing the soil’s modulus value directly. The settlement is calculated with conventional procedures using the improved modulus value.

12. Vibro Compaction Quality Control
Compaction point locations
Resistance level as measured by amp meter (vibrator draws
more current in denser soils)
Quantity of fill added or reduction in site level

13. Vibro Compaction Acceptance Testing
Standard Penetration Test (SPT)
Cone Penetrometer Test (CPT)
Pressuremeter Test (PMT)
Dilatometer Test (DMT)
Load test

14. Vibro Compaction Benefits
Increases bearing capacity and reduces foundation size
Reduces foundation settlement
Mitigates liquefaction potential
Permits construction on granular fills

15. Educational Resource Library
Vibro Replacement Stone Columns
Vibro Replacement Stone Columns extends the range of soils that can be improved by vibratory techniques to include cohesive soils. Densification and/or reinforcement of the soil with compacted granular columns or “stone columns” is accomplished.
© Hayward Baker Inc.,

16. Vibro Replacement Stone Columns
Educational Resource Library
Vibro Replacement Stone Columns
Cohesive, mixed and layered soils generally do not densify easily when subjected to vibration alone. The Vibro Replacement Stone Columns technique was developed specifically for these soils, effectively extending the range of soil types that can be improved with the deep vibratory process.
With Vibro Replacement Stone Columns, columns of dense, crushed stone are designed to increase bearing capacity, reduce settlement, aid densification and mitigate the potential for liquefaction, and improve shear resistance.
© Hayward Baker Inc.,

17. Vibro Replacement Stone Column Process
Educational Resource Library
Vibro Replacement Stone Column Process
© Hayward Baker Inc.,

18. Vibro Replacement Stone Column Construction
Educational Resource Library
Vibro Replacement Stone Column Construction
The two primary methods of Vibro Stone Column construction are:
Wet, Top Feed Method (Replacement and Displacement)
In this technique, jetting water is used to remove soft material, stabilize the probe hole, and ensure that the stone backfill reaches the tip of the vibrator. This is the most commonly used and most cost-efficient of the deep vibratory methods. However, handling of the spoil generated by the process may make this method more difficult to use on confined sites or in environmentally sensitive areas.
© Hayward Baker Inc.,

19. Vibro Replacement Top-Feed Construction Method
Educational Resource Library
Vibro Replacement Top-Feed Construction Method
© Hayward Baker Inc.,

20. Educational Resource Library
Vibro Replacement
Dry, Bottom Feed Method (Displacement)
This technique uses the same vibrator probes as standard Vibro Replacement Stone Columns, but with the addition of a hopper and supply tube to feed the stone backfill directly to the tip of the vibrator. Bottom Feed Vibro Replacement is a completely dry operation where the vibrator remains in the ground during the construction process. The elimination of flushing water in turn eliminates the generation of spoil, extending the range of sites that can be treated. Treatment is possible up to a depth of 80 feet and is not inhibited by the presence of groundwater.
© Hayward Baker Inc.,

21. Vibro Replacement Bottom-Feed Construction Method
Educational Resource Library
Vibro Replacement Bottom-Feed Construction Method
© Hayward Baker Inc.,

22. Vibro Replacement Design Steps
Educational Resource Library
Vibro Replacement Design Steps
1. Perform site investigation
Soil type, gradation, consolidation, and strength important
2. Calculate predicted improvement
Problem understood
3. Establish requirements of ground improvement
What settlements, factor of safety, etc., are allowable
4. Design Vibro Replacement scheme
Number of stone columns and/or performance requirements required to achieve desired results
5. Establish testing criteria
Load test, SPT, area of stone columns
© Hayward Baker Inc.,

23. Vibro Replacement Important Parameters
Educational Resource Library
Vibro Replacement Important Parameters
Ground conditions
Relative density
Degree of saturation
Permeation
© Hayward Baker Inc.,

24. Vibro Replacement Design Considerations
Educational Resource Library
Vibro Replacement Design Considerations
The design approach for Vibro technologies will generally be governed by one or more of the three major categories of site improvement:
Shear resistance increase
Settlement control
Liquefaction & lateral spreading mitigation
© Hayward Baker Inc.,

25. Vibro Replacement Design Considerations
Educational Resource Library
Vibro Replacement Design Considerations
© Hayward Baker Inc.,

26. Vibro Replacement Design Requirements
Educational Resource Library
Vibro Replacement Design Requirements
Design of the Vibro program requires information on:
Total loads (structure, surcharge, live, wind and seismic)
Soil type (variation, stratigraphy, groundwater location)
Type of footing/slab design
Structural settlement tolerance
Site restrictions and limitations
To address the above issues, the Vibro program is designed such
that the zone of influence of the vibratory probe ensures the
necessary soil densification and/or reinforcement.
© Hayward Baker Inc.,

27. Vibro Compaction Densification Results
Educational Resource Library
Vibro Compaction Densification Results
© Hayward Baker Inc.,

28. Vibro Replacement Expected Results
Educational Resource Library
Vibro Replacement Expected Results
© Hayward Baker Inc.,

29. Vibro Replacement Increased Bearing Capacity
Educational Resource Library
Vibro Replacement Increased Bearing Capacity
Vibro Replacement constructs dense, Vibro stone columns in the zone requiring improvement. The allowable bearing capacity can be calculated by a variety of methods, such as the one developed by Priebe in “The Design of Vibro Replacement”, Ground Engineering, December If any of the in situ soils are granular, their improved value should also be accounted for in the design.
© Hayward Baker Inc.,

30. Vibro Replacement Reduced Settlement
Educational Resource Library
Vibro Replacement Reduced Settlement
Vibro Replacement constructs high modulus dense Vibro stone columns in the zone requiring improvement. The anticipated settlement can be evaluated by a variety of methods, such as the Priebe method.
This method provides an improvement factor based on the stone column’s angle of internal friction and the percentage of the treatment zone replaced by stone (area replacement ratio).
In addition, if any of the in situ soils are granular, their improved parameters should also be included in the design.
© Hayward Baker Inc.,

31. Vibro Replacement Reduced Settlement
Educational Resource Library
Vibro Replacement Reduced Settlement
Method to estimate settlement reduction using stone columns in cohesive soils
© Hayward Baker Inc.,

32. Vibro Replacement Liquefaction Prevention
Educational Resource Library
Vibro Replacement Liquefaction Prevention
Seismic motion causes pore pressure to increase. When the pore pressure increases to equal interstitial grain-to-grain stresses, liquefaction is initiated. The soil then loses shear strength, resulting in bearing failures and slope instability, followed by large deformations (horizontal and vertical)
Site improvement by densification has proven to be the most effective solution. Densification will increase interstitial stresses, thus preventing liquefaction and settlement
Densification is required to preclude excessive settlements and offers the most secure remedy to multiple ground accelerations (aftershocks)
© Hayward Baker Inc.,

33. Vibro Replacement Embankment Subgrade Improvement
Educational Resource Library
Vibro Replacement Embankment Subgrade Improvement
Vibro stone columns increase the slope stability safety factor especially when they attract sufficient loading to increase shearing resistance. The shear strength of treated soil depends on the shear strength of the untreated soil, the transverse shear strength of the columns, the area replacement ratio and the load conditions.
© Hayward Baker Inc.,

34. Vibro Replacement Typical Arrangement of Stone Columns
Educational Resource Library
Vibro Replacement Typical Arrangement of Stone Columns
© Hayward Baker Inc.,

35. Vibro Replacement Quality Control
Educational Resource Library
Vibro Replacement Quality Control
Production Monitoring
Quantity and quality of backfill added
Vibrator amperage draw
Treatment depth
Post-Construction Testing
Standard Penetration Testing (SPT)
Cone Penetrometer Testing (CPT)
Dilatometer Testing (DMT)
Load Testing
Shear Wave Velocity Profiling
© Hayward Baker Inc.,

36. Vibro Replacement Benefits
Educational Resource Library
Vibro Replacement Benefits
Permits shallow footing construction
Reduces foundation settlement
Increases bearing capacity, allowing reduction in footing size
Mitigates liquefaction potential
Prevents earthquake-induced lateral spreading
Provides slope stabilization
Permits construction on fills
© Hayward Baker Inc.,

37. Dynamic Compaction Weights of 10 to 30 tons
Drop heights of 50 to 100 ft
Impact grids of 7 x 7 ft to 20 x 20 ft

38. Dynamic Compaction

39. Dynamic Compaction

40. Dynamic Compaction