Which two components contribute to soil strength?

• A. Dilation and Compaction
• B. Cohesion and Friction
• C. Weight and Density
• D. Plasticity and Viscosity

Answer: (B)

The correct choice, which identifies the two fundamental components that contribute to soil strength, is cohesion and friction.

Cohesion refers to the attractive forces between soil particles, which keep them together even in the absence of external pressure or forces. This property allows soils to resist shearing and contributes significantly to their overall strength. For example, cohesive soils, such as clay, have particles that are bound together by water molecules or electrostatic attraction, enhancing their stability and strength.

Friction, on the other hand, comes into play when soil particles are pressed against each other, especially under the influence of external loads. The interlocking between particles and the angularity of the grains determine the frictional resistance. When a load is applied, the particles resist movement primarily due to this friction. Sandy soils, which tend to have more angular particles, exhibit higher friction because of the way the grains interlock when piled together.

Together, cohesion and friction provide a comprehensive understanding of how soils can withstand various forces, making them critical factors in assessing soil strength. The other options, while related to different properties of soil, do not directly address the combination of forces that specifically contributes to soil strength. For instance, dilation and compaction pertain to changes in volume and density