What process uses a vibratory probe to densify cohesionless soils?

Vibratory compaction is the process that specifically utilizes a vibratory probe to densify cohesionless soils, such as sands and gravels. This method involves the application of vibrations to the soil, which reduces void spaces and increases density. The vibrations induce oscillations in the soil particles, allowing them to rearrange and settle into a more compact formation. This process is particularly effective for cohesionless soils because these types of soils do not rely on moisture or adhesive forces for stability, making them ideal candidates for densification through vibratory methods.

Dynamic compaction, while also a method for improving soil density, typically involves dropping heavy weights from a height to create shock waves that compact the soil; it does not specifically use vibratory probes. Static compaction relies on heavy machinery to compress the soil under static load, which may not be as effective for cohesionless materials without the enhancement provided by vibration. Grading refers to the process of leveling or shaping the ground rather than compacting soil to increase its density.

Overall, the distinction of vibratory compaction as the correct answer lies in its direct use of vibratory tools to achieve optimal soil densification specifically for cohesionless soils.