Soil Improvement techniques for
Marshy land
Following methods are used worldwide• Deep Mixing Method (DMM) /Mass Mixing Method
(MMM)/Mass Stabilizing Method (MSM)
• Stone columns
• Grouting
Deep Mixing Method(DMM)/Mass Mixing
Method(MMM)/Mass Stabilizing Method
(MSM)
• The deep mixing method/ mass mixing method involve blending a binder with soil in situ to
produce soil-cement that has improved properties, such as increased strength and reduced
compressibility, compared to the untreated soil.
• Binder materials for the deep mixing method can consist of cement, lime, fly ash, slag, or other
binder materials, as well as blends of binder materials. In current United States practice, cement
and slag-cement blends are the most common types of binder. When the binder is pre-mixed with
water to create a binder-water slurry that is then mixed into the ground, the process is called the
:wet mixing method.” When dry binder is delivered pneumatically, the process is called the “dry
mixing method.”
• Can be used in combination with Stone columns to support heavy structures
• Link - https://youtu.be/OqbDSgMJIJw
• Codal provision available - prEN 14679, Eurocode EN 1997
Deep Mixing Method(DMM)/Mass Mixing
Method(MMM)/Mass Stabilizing Method
(MSM)
Advantages
1.
The plan view arrangement of treatment, the treatment depth, and the degree of improvement to
strength and stiffness can be easily adjusted to satisfy design requirements and subsurface
conditions.
2.
Prevents liquefaction of loose sand deposits by increasing strength of soil.
3.
Powerful wet-mixing equipment can penetrate layers of dense and strong material totreat
underlying weak, loose, or compressible layers.
4.
Economical on large projects.
Disadvantages
1.
Limit is up-to 40m below ground level
2.
The wet method of deep mixing generally uses heavy equipment, which can require timber mats
or other techniques to enable equipment to operate on soft ground.
Deep Mixing Method(DMM)/Mass Mixing
Method(MMM)/Mass Stabilizing Method
(MSM)
• Used in Japan since 1970
• Live examples where Deep mixing method is implemented- Tokyo's Haneda Airport ,
expansion of the Hong Kong International Airport.
Images taken from Google and book GEO-E2080 Foundation Engineering and Ground
Improvement
Stone Column
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•
•
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Vibro- Replacement (Wet) - https://youtu.be/F_kI6vQ5_gE
Vibro- Displacement - https://youtu.be/XesKo2hHwu4
Rammed Stone Columns - https://youtu.be/5rn1DorMXNA
Stone columns can provide a highly cost-effective ground improvement treatment to strengthen,
stiffen and improve drainage in loose/soft ground strata.
• The process involves formation of compacted columns of clean granular material, typically coarse
gravel, penetrating to depth through the soft/loose strata.
Advantages
• Increased bearing capacity of the ground below shallow foundations and slabs.
• Reduced total and differential settlements of structures.
Disadvantages
• Maximum depth constraint is 165 feet
• Effective in granular and cohesion less soil
Codal provisions – Is 15284 – 1, ACI, IBC, ICC
Stone Column -Continued
• Used since 1950 in Europe and sine 1970 in US
Vibro- Replacement, Vibro- Displacement and Rammed stone column
Images taken from Google
Grouting
• Grouting comprises a set of geotechnical techniques to introduce materials with pressure, having the
objective of waterproofing and/or altering the physical characteristics of the soil or rock formation upon
setting.
• Soil Grouting
1. Permeation grouting (using particulate, colloidal or solution grouts) – Used in Japan since 1950
Link - https://youtu.be/C42m52LKgX8
2. Soil fracture grouting (including compensation grouting) – Used in US since 1990
Link - https://youtu.be/vKMYJZvUBVc
3. Compaction Grouting - Used in West since 1950
Link- https://youtu.be/mou95Ailfbk
4. Jet Grouting – Used in West since 1970
Link- https://youtu.be/bWnXUCk9Uv0
Advantages
• Has nearly unlimited configurations of column geometry.
• Can be used in a wide range of soil types and groundwater conditions and minimizes settlement.
Disadvantages
• Installation may cause ground heave
• Can be more difficult in plastic soils
Grouting - Continued
Codal provisions – IS 13094, IBC
Image taken from book GEO-E2080 Foundation Engineering and Ground Improvement