Foundation, Concrete and Earthquake Engineering

Technical Survey and Analysis for Foundation Repair or Retrofitting

At first we like to introduce technical survey and analysis required before taking decision for foundation repair and choosing method of foundation repair. Any types of retrofit work of large scale should be supervised by professional to evaluate structural and geotechnical conditions in and around the foundation. As extensive repair are very expansive we should be very careful about feasibility of repair and also method of repair and a detail survey followed by analysis is required.

Excavating trench for foundation to be retrofitted
A historical survey is required to have information about foundation or foundation walls. The extent of survey and subsequent analysis depend on the following:

  • Size of to be retrofitted building 

  • Age of building 

  • Condition of building foundation 

  • Change in use of buildings etc.
Seismic retrofitting of steel tank with concrete foundation
From this survey we will evaluate condition of foundation which will define whether a foundation can be retrofitted economically or not. We have already learnt about cost involvement in this process. A tolerable amount of cracks and tilts is considered enough not to retrofitted when settlement is stopped or further settlement is unlikely to happened. The analyses that should be carried before foundation repair are:

a. At first to evaluate soil conditions; to have this we can investigate government archives and construction records.

b. Survey for foundation walls and foundation as well

c. To collect damage report 

Exploring for foundation cracks
d. Visual survey of foundation and if required ground excavation should be carried out.

e. Crack survey

f. Foundation survey which includes drilling and testing etc.

g. Report of time dependent foundation settlement and settlements as well (precision settlement measurement, precision leveling)

h. Determining foundation load considering static system. This is determined from structural analysis of buildings.

i. Measurement of pore-water pressure
Moving away of structural joint as a sign of foundation settlement
j. Determining ground water table

k. Vibration measurements

l. Quality control of material

m. Straightening and leveling of foundation or other walls

n. Measuring stress in existing tension ribbon

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