Which type of foundation helps in mitigating differential settlement for tanks?

• A. Concrete slab foundation
• B. Gravel ringwall foundation
• C. Asphalt base foundation
• D. Wooden pile foundation

Answer: (B)

The gravel ringwall foundation is designed specifically to mitigate differential settlement for tanks. This type of foundation allows for more uniform distribution of loads across the underlying soil, which helps prevent uneven settling that can occur with other foundation types.

Using a gravel material equipped with a ringwall design offers flexibility and allows for some movement of the subgrades beneath the tank without transferring that movement directly to the tank structure. This is particularly important in areas where soil conditions may be variable or where moisture content changes could affect soil stability.

In contrast, while other foundation types such as concrete slab or asphalt may offer solid support, they can be less effective in accommodating soil movement, which may lead to stresses in the tank structure. Wooden pile foundations, while useful in certain conditions, do not provide the same benefits as gravel in terms of flexibility and load distribution.

Therefore, the gravel ringwall foundation is regarded as an effective method for not only providing a stable base for the tank but also for managing differential settlement risks, ensuring the tank remains structurally sound throughout its lifespan.