Which type of soil generally exhibits weak characteristics under load?

• A. Gravel
• B. Silt
• C. Clay
• D. Organic soils

Answer: (D)

Organic soils generally exhibit weak characteristics under load due to their composition, which includes decomposed plant material, peat, and other organic matter. This type of soil is typically less dense and more compressible compared to mineral soils. The presence of organic matter often leads to lower shear strength, higher compressibility, and greater potential for settlement when subjected to loads.

Because organic soils have high water retention capacities, they can become saturated easily, which further diminishes their load-bearing capacity. When loads are applied, these soils may exhibit significant deformation and may not effectively transmit loads to the underlying layers, making them less suitable for supporting structures without significant engineering measures or remediation.

In contrast, gravels and sands usually possess good load-bearing characteristics due to their coarser particles and better drainage properties. Clays can also exhibit weak characteristics, particularly when saturated, but they generally have more potential for strength when properly compacted or when they are in a drier state. However, organic soils remain the most problematic in terms of support under load, thus making them the correct answer in this context.