Which one of the following parameters can be used to estimate the angle of internal friction of a sandy soil?

Explanation :

• The angle of friction between soil particles depends upon the shape, size, roughness, grading, and packaging of particles.
• For Sand, particle size and shape roughly remain the same and thus it cannot be used to estimate the angle of friction of sandy soil.
• However, the angle of internal friction would be very high if the sand particle is compactly dense which is indicated by the value of the density index.
• The density index is the ratio of the difference between the void ratios of a cohesionless soil in its loosest state and existing natural state to the difference between its void ratio in the loosest and densest states.
• The higher value of the relative index indicates a higher angle of internal friction.

So we can say that parameter that can be used as a rough guide to determine the type of failure in the soil is the Angle of internal friction which is indicated by the value of the density index.