Stress Distribution in Soil MCQ with answer and solution

Concept

Newmark's influence chart is a graphical method used to determine the vertical stress at any point beneath a loaded area of arbitrary shape. Each small element on the chart represents an equal fraction of the applied stress, known as the influence factor.

Formula

If = 1 / (N × M)

Step-by-step solution

1. Identify the number of concentric circles (N = 10) and radial lines (M = 50) from the given data. 2. Calculate the total number of influence areas (fields) on the chart: Total fields = N × M = 10 × 50 = 500. 3. Compute the influence factor: If = 1 / (Total fields) = 1 / 500 = 0.002.

Explanation

The influence factor (or influence value) of Newmark's chart is given by the inverse of the total number of sectors (or fields) formed by the concentric circles and radial lines. Total fields = Number of concentric circles (N) × Number of radial lines (M). Therefore, Influence Factor = 1 / (N × M) = 1 / (10 × 50) = 1 / 500 = 0.002.

Shortcut

Remember that the influence factor is simply 1 divided by the product of the number of circles and radial lines.

Common mistake

Dividing the number of circles by the radial lines or vice versa, or forgetting that each sector represents a specific fraction of unity.