Chapter 2: Earthworks and Ground (1-15) ⑬👷♂️ [What is Ground Subsidence?]
- Why does the ground sink? An easy-to-understand explanation of causes and countermeasures -
The phenomenon where buildings or roads tilt or the ground level drops is called "ground subsidence."
In civil engineering and construction work, ground subsidence significantly affects the safety of structures, so it is important to understand the causes in advance and implement appropriate countermeasures.
In this article, we will explain "ground subsidence" in an easy-to-understand manner, covering its mechanisms, causes, and countermeasures.
What is ground subsidence?
Ground subsidence is
a phenomenon where the ground sinks due to compression of the soil or a decrease in groundwater
.
When the ground sinks, the buildings, roads, and bridges on top of it also sink along with it.
Image of ground subsidence
For example, if you press a sponge with your hand, it becomes thinner.
The ground is the same;
heavy loads are applied
groundwater decreases
soil is compacted
causing the volume to decrease and the ground to subside.
Main causes of ground subsidence
1. Load from buildings or embankments
When the weight of buildings or embankments acts on soft ground, the soil is compressed and settles.
Cohesive soil, in particular, is prone to consolidation settlement, which can continue over a long period.
② Groundwater pumping
When large amounts of groundwater are pumped out, the water pressure within the ground decreases.
As a result, soil particles pack together, causing the ground to shrink and subside.
In the past, ground subsidence caused by excessive groundwater use became a major issue in industrial areas.
③ Insufficient compaction
If sufficient compaction is not performed during embankment work, the soil may naturally settle after construction, leading to subsidence.
④ Formation of underground cavities
If cavities form underground due to damage to aging sewer pipes or soil erosion caused by groundwater, the ground may suddenly collapse.
What is differential settlement?
Among types of ground subsidence, "differential settlement" requires particular attention.
Differential settlement is
a phenomenon where only a part of a building settles
.
As a result,
the building tilts
cracks appear in the walls
doors and windows become difficult to open and close
pipes are damaged
and other problems occur.
The impact on structures is greater than when the ground settles uniformly.
What happens when ground subsidence occurs?
Impact on buildings
Tilting
Cracking
Foundation damage
Impact on roads
Road surface unevenness
Formation of puddles
Reduced passability
Impact on lifelines
Damage to water and sewage pipes
Damage to gas pipes
Impact on communication facilities
Measures to prevent ground subsidence
Conduct a ground investigation
Perform a ground investigation before construction to determine
soil properties
bearing capacity
Groundwater level
and other factors are checked.
Perform ground improvement
In the case of soft ground,
Surface improvement method
Deep mixing method
Sand compaction pile method
and others are used to strengthen the ground.
Perform proper compaction
In embankment construction, it is important to roll and compact sufficiently for each specified layer thickness.
Adopt pile foundations
For soft ground, a method of driving piles to the bearing stratum to transfer the load is adopted.
Exam preparation points
For the 2nd Grade Civil Engineering Construction Management Engineer exam,
✅ Ground subsidence
→ A phenomenon where the ground sinks
✅ Differential settlement
→ A phenomenon where only a part of a building settles
It is important to understand this difference.
Summary
Ground subsidence is,
"a phenomenon where the ground sinks due to compression of the soil"
is.
The main causes include:
Load from buildings and embankments
Pumping of groundwater
Insufficient compaction
Formation of underground cavities
and others.
Since ground subsidence causes significant damage to buildings and roads, preliminary ground surveys and appropriate construction are essential.
To build safe structures, it is important to correctly understand the mechanisms of ground subsidence.
#CivilEngineeringConstructionManagementEngineer #Grade2CivilEngineeringConstructionManagementEngineer #Grade1CivilEngineeringConstructionManagementEngineer #CivilEngineering #ConstructionIndustry #ConstructionManagement #SiteSupervisor #Earthworks #GroundSubsidence #DifferentialSettlement #SoftGround #GroundSurvey #GroundImprovement #ConsolidationSettlement #BearingCapacity #SoilBearingStrength #EmbankmentWork #FoundationWork #CivilEngineeringTerms #TaigaConstructionNotes