Issue 1 V1.08
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Loaded Circular Area - Westergaard's Layered Soil

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Centrally Located Circular Area in Layered Soil

Notation and Units

Metric and Imperial Units

The above formulas may be used with both imperial and metric units. As with all calculations care must be taken to keep consistent units throughout with examples of units which should be adopted listed below:


  • B = width of foundation, ft or m
  • IW = Westergaard stress co-efficient
  • q = load per unit area, kip/ft2 or kN/m2
  • r = radius of loaded area, ft or m
  • z = vertical distance from load to point of interest, ft or m
  • µs = Poisson’s ratio of the soil between the reinforcements
  • ∆σ = stress increase at point of interest, kip/ft2 or kPa