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Ground Improvement Dr. Talat Bader

Ground Improvement Dr. Talat Bader. Dynamic Compaction. Dynamic Deep Compaction. Dynamic compaction was first used in Germany in the mid-1930’s. Menard technique France Dynamic Deep Compaction is simply the dropping of heavy weights on ground surface to densify soils at depth.

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Ground Improvement Dr. Talat Bader

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  1. Ground ImprovementDr. Talat Bader

  2. Dynamic Compaction

  3. Dynamic Deep Compaction • Dynamic compaction was first used in Germany in the mid-1930’s. • Menard technique France • Dynamic Deep Compaction is simply the dropping of heavy weights on ground surface to densify soils at depth

  4. Why Dynamic Deep Compaction • Reduce foundation settlements • Reduce seismic subsidence • Permit construction on fills • Densify garbage dumps • Improve mine spoils • Induce settlements in collapsible soils

  5. h w } Important Construction Conditions • The Drop Weights ranges from 8 to 200 tons • Drop Heights ranges from 50 to 100 ft. • Impact grids of 7 x 7 ft to 20 x 20 ft • Minimum 100-150 ft clearance from any structure • Review site for vibration sensitivity • Primarily for silts and sands but also clays

  6. Problems near groundwater Multiple passes to compact at depth Limitations

  7. Effect of Drop on the Ground

  8. Important Terms • Effective Depth -- Maximum depth of ground improvement • Zone of Major Densification -- About upper 2/3 of effective depth • Energy Level -- Energy per blow (weight times drop height) • Energy Intensity Factor -- Involves energy level, spacing, and number of blows

  9. Depth of Influence w = Weight of drop (Tons) h = Height of drop (m) D = Depth of influence (m) C = Factor= .3-.7 Depends on soil type From Holtz and Kovacs, 1981

  10. Dynamic compaction

  11. Dynamic Compaction

  12. Important Geotechnical Parameters • Soil conditions • Groundwater level • Relative density • Degree of saturation • Permeability

  13. Quality Control • Crater depths (map) • Surface elevation monitoring • Decrease in depth of weight penetration with successive drops • Pore pressures • Geophysical monitoring

  14. Question Time Thank you Dr. Talat Bader

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