Jun 01, 2018 · Record the number of blows required to effect each 15 cm (6 inches) of penetration. The first 6 inches is considered as seating drive. 5. The number of blows required for the second and third 15 cm (6 inches) of drive added is recorded as the penetration resistance value N of the soil.
Feb 07, 2016 · The sum of the number of blows required for the second and third 6 in. of penetration is reported as SPT blowcount value, commonly termed "standard penetration resistance" or the "N-value". The N-value provides an indication of the relative density of the subsurface soil, and it is used in empirical geotechnical correlation to estimate the approximate shear strength properties of the soils.
Nov 27, 2015 · Standard Penetration Test (SPT) Procedure Aim. To perform standard penetration to obtain the penetration resistance (N-value) along the depth at a given site. Equipment & Apparatus. Tripod (to give a clear height of about 4 m; one of the legs of the tripod should have ladder to facilitate a person to reach tripod head.) Tripod head with hook; Pulley.