Concrete Foundation Depth

In this construction video tutorial, the renowned civil engineer, Mr. Sami Ullah, has provided some useful guidances on how to determine the depth of any foundation.

In this video tutorial, Rankin’s formula is used to find the proper depth as depth of foundation is dependent on various factors like types of loads, types of soils with different bearing strength etc.

Rankin’s formula :-

Here,
D denotes depth of foundation
P denotes load operates on foundation or load of structure
W denotes unit weight of soil or thickness of soil
θ denotes angle of repose or internal friction of soil

Now, the calculation is done on the basis of the following data :-
Load of structure (taken as P) = 55 KN/m² (KN = kilo newton)
Density of soil = (taken as W) = 16 KN/m³ (there are various types of soils with different densities)

Density of dry soil = 25 to 35 KN/m³
Internal friction angle of dry soil θ = 20 degree
Density of wet soil = 15 to 25 KN/m³
Internal friction angle of dry soil θ = 19.2 degree

To learn the detail calculation process, go through the following video tutorial.

Video Source: Civil Engineers