What type of soil typically presents the highest risk for cave-ins?

Loose or granular soils, such as sand, are known to present the highest risk for cave-ins during excavation activities. This is primarily because these types of soils lack cohesive strength, which means they do not hold together well when disturbed. When conditions change, such as during rainfall or when they are excavated, loose or granular soils can shift suddenly and collapse, leading to hazardous situations.

In contrast, clay soil generally has cohesive properties that can provide some stability, albeit with its own risks. Rocky soil is typically more rigid and offers more resistance to shifting, thus posing a lower risk of cave-ins. Silty soil can also exhibit some cohesive properties but is typically less stable than clay. Loose or granular soils are particularly problematic because the particles can easily slide past one another, increasing the chance of a cave-in when there is not adequate support in place.