Standard Penetration Test

An in‑situ geotechnical test in which a standard split‑barrel sampler is driven into soil by a falling weight and the number of hammer blows required to advance the sampler a defined distance (commonly the blows for the final 300 mm) is recorded as the N‑value; the N‑value is an empirical measure of near‑surface soil resistance used for relative density, settlement and bearing‑capacity correlation