Newmark's chart is a term for an illustration that is used to determine the vertical pressure at any point situated below a uniformly loaded patch of soil. The soil can be any shape as long as it is uniformly loaded. Newmark's chart is used in soil science and draws its effectiveness from the theory of elasticity, which states that a material will return to its original shape after the stress that made it deform is removed. Newmark's chart is made up of concentric circles evenly spaced by radial lines. The chart can be useful for solving vertical stress problems, particularly when you want to determine the vertical pressure beneath any uniformly loaded area.
Verify the depth below the soil where the stress increase should reach to. Plot a plan of the uniformly loaded soil area with a scale where any given point (z) is equal to the unit length between the concentric circles on Newmark's chart.
Add the points (z) to a copy of Newmark's chart with a pencil. Position a point deeper than the spot that the stress increase reaches to in the centre of the chart.
Count the number of elements on Newmark's chart which are located inside of your plotted soil area, understanding that the chart contains 200 elements on it but that not all 200 will fall within your plotted area.
Use the information on Newmark's chart, which you plotted to solve an equation that yields the increase in pressure at the soil depth you're examining (" [?σ]_z"). Plug your values into the equation on a piece of paper that says: [?σ]_z=(IV)qM where IV = influence value, q = pressure on the loaded area and M = the number of elements enclosed by the loaded area.