Which of the following is an effective method for soil stability?

Dry compaction is an effective method for soil stability because it increases the density of the soil without the presence of water, which can lead to better load-bearing capacity and resistance to erosion. When soil particles are compacted together using mechanical means such as rollers or plate compactors, the voids between the soil particles are minimized, resulting in a more stable and sturdy foundation.

In situations where moisture is present (such as with wet compaction), soil may become less stable and more susceptible to movement or collapse, especially in loose or sandy conditions. Excavation, while important in construction, does not directly contribute to soil stability and can disturb existing soil structures. Soil grading is essential for drainage and managing surface water but does not specifically enhance soil density and stability like dry compaction does. Therefore, dry compaction is a crucial practice in ensuring that the soil can adequately support structures and remain stable under various conditions.