1. CE 486 DEEP COMPACTION Name : Ali Hamood Al-teeb. ID : 423103457
KINGDOM OF SAUDI ARABIA KING SAUD UNIVERSITY CIVIL ENGINEERING DEPARTMENT
CE 486 DEEP COMPACTION
Name : Ali Hamood Al-teeb.
ID :

2. Outlines Definition. Why Compact. Methods of deep compaction.
Vibro-Replacement Stone Columns.
Dynamic Compaction.
Preloading .
References.

3. Soil Compaction Definition:
It is the densification of soil by removal of air, which requires mechanical energy. Simplistically, compaction may be defined as the process in which soil particles are forced closer together with the resultant reduction in air voids.

4. Why Compact? Increases load-bearing capacity.
Prevents soil frost damage.
Provides stability.
Reduces water seepage, swelling and contraction.
Reduces settling of soil.

5. Vibro-Replacement Stone Columns. Dynamic Compaction. Preloading .
Methods of compaction
Vibro-Replacement Stone Columns.
Dynamic Compaction.
Preloading .

6. Vibro-Replacement Stone Columns
Vibro-Replacement Stone Columns extends the range of soils that include cohesive soils.
Densification and/or reinforcement of the soil with compacted granular columns or “stone columns” is accomplished by either top-feed or the bottom-feed method.
Cohesive, mixed and layered soils generally do not densify easily when subjected to vibration alone. The Vibro-Replacement Stone Column 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.

7. The Vibro-Replacement Stone Column Process:
Reduces foundation settlement.
Increases bearing capacity, allowing reduction in footing size.
Provides slope stabilization.
Permits construction on fills.
Permits shallow footing construction.

8. Vibro-Replacement Procedures:
Stage1: The jet at the bottom of the Vibroflot is turned on and lowered into the ground
Stage2: The water jet creates a quick condition in the soil. It allows the vibrating unit to sink into the ground

9. Vibro-Replacement Procedures (cont.):
Stage 3: Granular material is poured from the top of the hole. The water from the lower jet is transferred to he jet at the top of the vibrating unit. This water carries the granular material down the hole

10. Vibro-Replacement Procedures (cont.):
Stage 4: The vibrating unit is gradually raised in about 0.3-m lifts and held vibrating for about 30 seconds at each lift. This process compacts the soil to the desired unit weight.

11. Dynamic compaction Definition:
method involves the systematic dropping of heavy weights, 100 to 400kN, from a height of 5 to 30m, in a pattern designed to remedy poor soil conditions at the proposed building site.

12. Why dynamic compaction is used?
To increase in-situ density.
Improve the bearing capacity and consolidation characteristics of soils (or waste materials).
Improve in-situ permeability and/or reduce liquefaction potential.

13. What soils are suitable?
Most soil types can be improved, including silts and some clays.
The most commonly treated soils are old fills and granular virgin soils. Soils below the water table are routinely treated.
Careful control has to be used to allow dissipation of excess pore pressures created during the weight dropping.

14. How much improvements is possible?
The total degree of improvement is dependent on the total applied energy to the ground.
Empirical correlations have been established between soil type, test parameters (such as SPT, CPT and PMT) and the total applied energy.

15. Stages of the process?
Stage1 : Prior to commencement of the works, a granular blanket is placed over the treatment area. The weight is dropped from heights of up to 25m, with up to 5 no. passes and up to 10 no. drops per pass.
Stage2 : On the first pass the deepest layers are compacted. Following completion of the pass the site is then regarded.

16. Stage3 : Subsequent passes compact successively shallower layers, following which the site is regarded.
Stage4 : The final tamping pass is often continuous to compact the soils at shallow depth.

17. Preloading Known as “pre-compression”.
It is the process of placing additional vertical stress on a compressible soil to remove pore water over time. The pore water dissipation reduces the total volume causing settlement.
the consolidation of the soils is time dependent , delaying construction projects making it a non-feasible alternative

18. Soils Treated:
Organic Silt.
Silts and Clays.
Soft Clay.
Dredged Material.
Design Considerations:
Bearing Capacity
Slope Stability
Degree of Consolidation

19. Applications
Reduce Post-Construction Settlement
Reduce Secondary Compression
Densification
Improve Bearing Capacity.

20. References http://tc17.poly.edu/preloading.html