Study on SPT N-values and relative density through various soundings in full-scale chamber test ground

Abstract

In Japan, the evaluation of ground strength, such as the liquefaction resistance, is often carried out through the N-value of the standard penetration test (SPT), and it is used in various designs. Other soundings are also used, including the cone penetration test (CPT) and the Swedish weight sounding (SWS) that is comparatively simpler when compared with SPT, and conversion formulae to N-value have also been proposed by various researchers. In this paper, the various soundings described above (SPT, CPT, and SWS) were carried out in a sandy ground, where the density was controlled and measured by Radio Isotope (RI) method. Then, the correlation between the SPT N-value and the relative density Dr was examined. Based on the results, the N-Dr correlation was examined using the results of various soundings in a full-scale chamber test where the ground density was controlled. The results confirmed the applicability of the correlation formulae, with good correlation confirmed not only between Dr and SPT N-value, but also with the N-value estimated from each sounding.