Chapter 3 Ground Improvement Works (1-13) ③👷♂️ [What is the Sand Compaction Pile Method]
The Sand Compaction Pile (SCP) method is a ground improvement technique that enhances the strength and stability of the ground by creating compacted sand piles within soft ground.
By creating pile-like structures while injecting sand into the ground, the surrounding soft soil is compressed and compacted, aiming to improve bearing capacity and suppress settlement.
It is a method widely used as a countermeasure for soft ground, such as cohesive soil or reclaimed land.
Why is the Sand Compaction Pile method necessary?
Soft ground contains a lot of moisture and is easily compressed, so if structures are built on it as is, problems such as:
ground subsidence occurring
differential settlement occurring
embankments becoming unstable
liquefaction occurring during earthquakes
may arise.
In the Sand Compaction Pile method, sand piles are created within the ground to increase ground density and improve it into safe ground.
Mechanism of the method
A casing pipe is inserted into the ground using specialized machinery, and sand is fed into it.
Afterward, the sand is pushed out and compacted while applying vibration and pressure to create sand piles.
At this time, the surrounding soft ground is also compressed, leading to:
increased ground density
increased bearing capacity
Consolidation promotion
Liquefaction prevention
These effects can be achieved.
Construction Procedure
① Surveying of construction position
Determine the construction position based on the design drawings.
② Penetration of casing pipe
Penetrate to the specified depth using a vibrator.
③ Sand charging
Charge sand into the pipe.
④ Sand pile formation
Compact the sand while pushing it out to form a sand pile.
⑤ Repeated construction
Complete the improvement by constructing the specified number of sand piles.
Effects of the Sand Compaction Pile Method
① Bearing capacity improvement
The ground density increases, allowing it to support larger loads.
② Settlement suppression
Promote consolidation settlement in advance to reduce settlement after completion.
③ Ground strengthening
The sand piles and the surrounding ground become integrated, improving stability.
④ Liquefaction Countermeasures
Prevents liquefaction by increasing the density of sandy ground.
Advantages
✅ Can significantly improve bearing capacity
✅ Effective for settlement control
✅ Effective as a liquefaction countermeasure
✅ Suitable for large-scale ground improvement
✅ Also used in large-scale projects such as ports and airports
Disadvantages
⚠ Vibration and noise occur during construction
⚠ Construction machinery is large
⚠ Difficult to construct in narrow spaces
⚠ Requires securing a supply of sand
⚠ Constructability is influenced by ground conditions
Applicable Sites
The sand compaction pile method is utilized in the following types of construction:
Port construction
Airport construction
Land reclamation
River embankments
Road embankments
Railway embankments
Tank foundations
Liquefaction mitigation works
This is a construction method particularly suitable for large-scale soft ground improvement.
Key points for exams
In the Second-Class Civil Engineering Construction Management Technician exam,
Method of creating sand piles
Soft ground improvement
Consolidation promotion effect
Liquefaction mitigation method
Mechanism for improving bearing capacity
and similar topics are frequently asked.
In particular,
the characteristic of being a "method that creates sand piles to compact the surrounding ground"
is an important exam point.
Differences from the Paper Drain Method
Item | SCP Method | Paper Drain Method | Material Used | Sand | Drain Material | Bearing Capacity Improvement | ◎ | △ | Consolidation Promotion | ◎ | ◎ | Liquefaction Mitigation | ◎ | × | Improvement Effect | Large | Focus on Drainage Promotion
Summary
The Sand Compaction Pile method is a representative ground improvement technique that creates compacted sand piles in the ground to improve the bearing capacity of soft ground, suppress settlement, and provide countermeasures against liquefaction.
It is widely used in large-scale civil engineering projects such as ports, airports, roads, and embankment construction, and is an important term that frequently appears in the Second-Class Civil Engineering Construction Management Engineer examination.
Be sure to remember the key point: it is a 'method of compacting the ground using sand piles'.
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