Empirical Correlation between SPT N-Value and Relative Density for Sandy Soils

Abstract

ABSTRACT It has been known that the penetration resistance depends on the grain size of soils, and that fines-containing sands have smaller SPT N-values than clean sands. Previous investigations on the link between the penetration resistance and relative density have indicated that the ratio between the normalized N-value and the square of the relative density, N1/D2r, is dependent on the grain size of sands. While this dependence has not been properly quantified, it has been customary to utilize the well-known expression of Meyerhof with N1/D2r being fixed at 41. In this paper, an attempt was made to correlate the penetration resistance and relative density by accounting for the grain size properties of soils. The void ratio range (emax – emin) was used as a measure indicative of the grain size and grain size composition. It was found that M is highly dependent on the value of (emax – emin) and that this ratio gradually decreases with increasing void ratio range from a value of about 100 for gravels to a value of about 10 for silty sands. This dependence is mathematically formulated and used to establish an empirical correlation between the SPT TV-value and Dr that is applicable to various kinds of soils ranging from silty sands to gravels. The correlation is developed by using data of high-quality undisturbed samples and results of SPT measurements on natural deposits of sandy soils and gravels.