What action indicates that a pile is effectively refusing to be driven into the soil?

The action that indicates a pile is effectively refusing to be driven into the soil is represented by the scenario where there is a specific amount of movement, such as 20 strikes resulting in only 1/8 inch of movement. This phenomenon signifies that while there may be some initial penetration into the soil, the resistance is substantial, preventing the pile from being driven further.

In piling operations, small movements relative to the force applied and the number of strikes can be indicative of soil conditions, such as compacted ground or rock layers, that are resisting further penetration. Thus, this limited movement, despite multiple strikes, shows that the pile is meeting significant resistance, effectively refusing to be driven deeper.

In the context of the other options, movements of 1/4 inch with repeated strikes or being stable after initial drives may not definitively indicate refusal if there is some degree of penetration or movement. Similarly, exceeding the strike count without movement can also occur under other conditions, such as pile alignment or equipment failure, without specifically indicating refusal. The option showing a combination of significant strikes with minimal movement best exemplifies the condition of refusal.