This article describes how to calculate the dimensions of the foundation. We will calculate the depth and width of the foundation.
Foundation Depth Calculation
For all types of foundations minimum depth required is calculated
using Rankine’s Formula:
Where p = safe bearing capacity of soil
w = unit weight of soil
ϕ = angle of repose of soil.
However in any scenario it is not less than 0.9 meter.
Finding accurate safe bearing of the soil is an expert’s job, and it is found after conducting tests in field or in Laboratories.
I have shown general values for common types soils in the image as given below.
Foundation Width Calculation
To determine the width of wall foundations or size of column footing, one should first calculate the expected load and then divide it by SBC.
Width of wall foundation = Load per unit length of wall / S.B.C. of soil
Area of column footing = Load carried by column / S.B.C. of soil