Underpinning

What is underpinning?

  • Strengthening and stabilising the foundation of an existing building
  • Installation of temporary or permanent support
  • Provides additional depth or increase bearing capacity

When do we need underpinning?picture2

  • Construction of a new building adjacent to the old one
  • Settlement of an existing building
  • Change in how a structure is used
  • Need to add a basement below an existing building

Temporary support with maintenance jacking

  • Light structures may be supported with timber or concrete mats
  • If settlement occurs, mechanical or hydraulic jacks keep the structure level

Bracket pile underpinning

picture5

  • Steel bracket piles driven adjacent to the structure
  • Load is transferred from the structure into the pile through a steel bracket
  • Backfilled with lean sand cement mix

Minipiles

picture6

  • Minipiles inserted through the existing foundation
  • Generally do not require temporary support of the building

New foundation wall and footing constructed underneath the existing foundation

  • The area is excavated
  • The new footing is constructed
  • The excavated area is backfilled

Support during underpinning

  • Digging trenches at intervals
  • This leaves most of the foundation supported by the soil

Support during underpinning

picture9

  • Using needle beams
  • Beams are threaded through holes cut in the wall
  • Entire wall can be exposed at once

 

See More  Precast Concrete Stairs Construction