Which equipment is most effective for compacting granular soils like sand and gravel?

The smooth-wheel roller is particularly effective for compacting granular soils such as sand and gravel due to its design and functionality. This type of roller operates with a wide and flat wheel surface, which helps distribute the weight evenly over the soil surface. This leads to better compaction without causing displacement of the granular material. As it moves forward, the smooth surface of the roller applies static load, which increases the density of the soil by rearranging the particles closely together.

Granular soils benefit from vibration and pressure applied in this manner because they have less cohesion compared to cohesive soils like clay. The smooth-wheel roller is effective in bringing the particles closer together, minimizing voids and maximizing stability.

In contrast, other options such as the sheepsfoot roller are better suited for cohesive soils, while a plate compactor, although effective for small areas and more localized compaction, may not provide the broader, uniform compression needed for larger areas of granular material. The array roller is not commonly referenced in standard compaction methods and would not be suitable for granular soils. Therefore, the design and operating principle of the smooth-wheel roller make it the most appropriate choice for this task.