Determination of stresses and deflection using Iwanows nomographs

1 Determination of stresses and deflection using Iwanow s nomographs 

It must be stated that Iwanow s nomographs are valid for the Poisson ratio of the first and second layer equal to 0.25 (pi = ii = 0.25) and for the Poisson ratio of the third layer equal to 0.35 (p3 = 0.35). 

The vertical stress developed at the bottom surface of the second layer (almost equal to the stress developed at the top of the subgrade), a 2 is calculated using the following equation  

The radial horizontal stress at the bottom of the first layer (asphalt layers), is calculated using the following equation  

The deflection at the surface of the subgrade, w, and at the centre of the loading surface can be calculated by the following equation  

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