Hi devilart, This method is used to compute the vertical and horizontal stresses of any shape ,irregular geometry below any point outside or inside
The chart as shown in the above figure essentially consists of n no. of radial lines and m no. of concentric circles.
To find out vertical stress at any point below or outside the loaded area, Plan of the loaded area is drawn such that depth Z at which stress is being computed equals the length AB as shown on
N = No. of blocks. Bina Nusantara.
Further, the plan is placed over influence chart such that the point below which stress is required coincides with the center of chart Then count the number of influence area (N) covered by the plan