The continuous impact dynamic penetration test is a sounding technology that uses the continuous impact excavation mechanism of  RPD (rotary percussion drill) to measure the impact penetration resistance (P value) of the ground and at the same time collect soil samples.

 P-value: The number of RPD hits required for the tip sampler to penetrate the ground to any depth. In addition, in the case of high-strength ground such as improved ground and soft rock, water supply rotary impact with a small bit may be used together.