What do geological teams do with dragon nails?

The purpose of the geological team to cut the dragon nail is to carry out geological exploration. Dragon-cutting nail is a kind of long steel nail, which is usually used in geological exploration. By laying dragon nails underground, geological teams can use them to measure underground geological structure, rock stability or groundwater level information. The principle of nail cutting is to judge the change of underground geology by using the length change of nails exposed to the surface.