What are the Types of Foundation Settlement?

Do you think foundation of structure settle due to design fault? Whatever you think; we think that this is very rare case where foundations settle due to structural design (under design).
So why do foundations settle? Commonly foundation settlement due to change are occurred or rendered to foundation soils that support foundation or structure and sometimes soils surrounding them.
Now what is settlement? Settlement is downward displacement (permanent) of foundation. ‘Permanent’ term is used as in active clay the cyclic downward displacement and heaving can be occurred.
Foundation settlement due to clay consolidation
The types of settlement are:
a. Settlement due to weight of structure directly
b. Settlement caused by secondary influences

a. Settlement due to weight of structure directly: 

This is the first type of foundation settlement and induced due to weight of structure directly.
Say weight of structure may result consolidation of underlain clay layer or may cause densification of loose sand deposit as consequence of compression.
Settlement analysis should be based on precisely determined dead load from structure. Dead load include structural weight from
• Beams
• Columns
• Floors
• Roofs
• Additional loads from fixed members.
In addition to dead load, live load can also result settlement in foundation of structure.

Live load includes weight of members that are considered non-structural component of structure like





Live load can also result foundation settlement. Say if propose structures or part of the proposed structure is used as library, the live load or additional live load is weight of books-this weight may have contribution to settlement of foundation.
Foundation undermining due to flowing water


Similarly if the proposed structure is used as warehouse, the analysis and design of structure must include true weight of expected items that will be stored there. So they contribute to settlement of foundation.
In some projects live loads become a considerable part of total load, like large towers for electric transmission or other tower for radio signal processing. In this structures, wind loads draw significant attention from engineering, here live load (as wind) have to consider in settlement analysis.
Foundation undermining due to adjacent excavation


As a whole, in settlement analysis should consider actual weight (dead) of structure and in appropriate cases including live loads. Here also considerable judgment and experience are required for determining loads for such analysis.
b. Settlement caused by secondary influences:
This cause includes
  • Failure of collapsible soil underground infiltration


  • Yielding of excavation done adjacent to foundation


  • Failure of underground tunnels and mines


  • Collapse of cavities of limestones


  • Undermining of foundation while flood


  • Earthquake induced settlement


  • Due to extraction of ground water and oil.



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