What type of soils have uniformity coefficients greater than 10 and a continuous range of particle sizes?

Well-graded soils are characterized by a wide range of particle sizes that are uniformly distributed, allowing for efficient packing and minimal void spaces. This quality contributes to their overall strength and stability, making them ideal for various civil engineering applications, such as foundation support and pavement construction.

A uniformity coefficient greater than 10 indicates that the soil contains a good mixture of both fine and coarse particles, avoiding large gaps between different sizes—which is a characteristic of well-graded soils. The continuous range of particle sizes helps to fill the voids between larger particles with smaller particles, resulting in a denser and more stable soil structure.

In contrast, uniformly graded soils typically have similar particle sizes, which can lead to inefficiencies in packing and increased void ratios. Gap-graded soils have a specific range of particle sizes that skips certain sizes, thus creating voids that are not filled adequately. Poorly graded soils, on the other hand, have a narrower range of particle sizes and often lack the necessary interparticle friction required for stability.

Thus, the defining features of well-graded soils, including their uniformity coefficient and continuous range of particle sizes, play a critical role in their structural performance and engineering applications.