Which type of soil cannot be classified as Class A if it has been previously excavated, is fissured, or subjected to vibration?

Granular soil, which typically includes materials like sand and gravel, is generally classified as Class A when it is stable and in its natural state. However, if granular soil has been previously excavated, fissured, or exposed to vibration, its structure and stability can be compromised. This can lead to increased risks of collapse or failure during excavation, as the factors mentioned disrupt the natural cohesion and compaction of the soil, making it less reliable.

In the context of excavation safety, Class A soil is recognized for its ability to maintain stability under excavation conditions. Therefore, when granular soil experiences changes that affect its integrity, it cannot be classified as Class A. It is essential to reassess the stability of the soil, considering the conditions that alter its uniformity and weight distribution.

Other types of soil, like cohesive, inert, or Type B soils, may have different stability characteristics under similar conditions, but the key point is that the defining features of Class A soil are entirely negated when it experiences structural changes, making granular soil an unsuitable candidate for this classification in such circumstances.