The number of blows per foot required to drive a standard penetration test (SPT) soil sampler into the ground during geotechnical exploration. The N-value is often used to estimate in situ consistency of clays and silts and relative density of sands.
Method of excavation of a trench up to 100mm wider than the outside diameter of the service to be installed, usually employing either a rockwheel or chain type trencher.
An axis of no stress.
Size of pipe or shaft used to define the internal working diameter.
To classify a value into an established range or category.