Spt n value correction. Therefore when SPT is performed in saturated silts and fine sands and if the observed N-value is more than 15, a correction has to be applied to reduce the observed values. Based on several suggestions, a reference value of 60% of the theoretical free-fall energy is used to adjust N-values to a common reference point. Aug 25, 2024 ยท To estimate the bearing capacity of a foundation using SPT data, engineers must first determine the corrected N-value (N 60) for the soil at the foundation level. This correction is applied on the N-value corrected for over burden pressure (N’). The relation given by Liao and Whitman (1986) is one of the most commonly used. Applies a correction to the SPT N value to account for the effect of effective overburden pressure in granular soils. The correlations use Standard Penetration Test (N) values corrected for overburden and hammer efficiency (N160). The standard penetration number is corrected for dilatancy correction and overburden correction. The SPT was originally developed from wash boring techniques. g. sup kwxl 7ca su wvye8tt escoa rao udpe taq euorxo4