As the void ratio (e) increases, what happens to strength?

• A. Increases
• B. Decreases
• C. Remains the same
• D. Varies

Answer: (B)

When the void ratio (e) increases, the strength of soil generally decreases. This is because the void ratio is a measure of the amount of void space in a soil mass compared to the solid particles. As the void ratio rises, it indicates that there is more space between the soil particles, leading to a reduction in their inter-particle contact and cohesion.

In soil mechanics, strength is often linked to factors such as the effective stress and the arrangement of soil particles. Higher void ratios tend to signify a looser, less compact state of the soil, which can diminish the overall strength and stability when subjected to loads. The soil becomes more susceptible to deformation and failure under external forces because the ability of the particles to resist displacement is reduced. Therefore, an increase in void ratio typically corresponds with lower shear strength and bearing capacity of the soil.

Understanding this relationship is crucial in geotechnical engineering, as it aids in predicting the behavior of soil under various loading conditions and helps in design considerations for foundations and other structures.