| Compaction Grouting |
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- Karstic Regions
- Rubble Fill
- Poorly Placed Fill
- Loosened Soil: Pre-Treatment
- Loosened Soil: Post-Treatment
- Liquefiable Soils
- Collapsible Soils
- To Compensate for Ground Loss During Tunneling
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- Drill or drive casing
- Location very important
- Record ground information
from casing installation
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- Typically bottom up but can
also be top down
- Grout rheology important (low mobility, not necessarily low slump)
- Usually pressure and/or volume
of grout limited
Slow, uniform stage injection
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- On-site batching can aid control
- Grout rheology important
- Pressure, grout quantity, injection rate, and
indication of heave are controlling factors
- Sequencing of plan injection
points very important
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| Several conditions must exist
in order for compaction grouting to yield its best results: |
- The in situ vertical stress in the
treatment stratum must be sufficient to enable the grout
to displace the soil horizontally (if uncontrolled heave
of the ground surface occurs densification will be minimized).
- The grout injection rate should
be slow enough to allow pore pressure dissipation.
Pore pressure dissipation should also be considered in hole spacing and sequencing.
- Sequencing of grout injection is
also important. If the soil is not near saturation, compaction
grouting can usually be effective in most silts and clays.
- Soils that lose strength during
remolding (saturated, fine-grained soils; sensitive clays)
should be avoided.
- Greater displacement will occur
in weaker soil strata. Exhumed grout bulbs confirm that
compaction grouting focuses improvement where it is most
needed.
- Collapsible soils can usually be
treated effectively with the addition of water during drilling
prior to compaction grout injection.
- Stratified soils, particularly thinly
stratified soils, can be cause for difficult or reduced
improvement capability.
- Rate of tunnel advance and tunneling method (in case of compensation grouting).
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- Pinpoint treatment
- Speed of installation
- Wide applications range
- Effective in a variety of soil conditions
- Can be performed in very tight access
and low headroom conditions
- Non-hazardous
- No waste spoil disposal
- No need to connect to footing or
column
- Non-destructive and adaptable to
existing foundations
- Economic alternative to removal
and replacement or piling
- Able to reach depths unattainable
by other methods
- Enhanced control and effectiveness
of in situ treatment with Denver System™
- Minimal impact to surface environment
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Quality control includes procedural inspection and documentation of the work activity, testing to ensure proper mix design/injection rates, and verification of ground improvement where applicable.
Ground improvement can be assessed by Standard Penetration Testing, Cone Penetrometer Testing, or other similar methods. Data recording of important grouting parameters has been utilized on sensitive projects. |
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