Ball penetration test for characterisation of soft clays

Abstract

The applicability of the ball penetration test (BPT) for identifying soil layering and evaluating several key geotechnical properties was studied. BPT and piezocone test data at four sites were evaluated and correlated with field and laboratory test results. Both ball and cone resistances were effective in evaluating soil layering. However, the larger transition zone induced by the ball deteriorated the linear variation of the effective overburden stress with depth. The ball factor effectively differentiated the depositional units of Korean clays better than the Japanese clays. The preconsolidation stress and the shear wave velocity Vs (or shear modulus G0) correlated well with the ball and cone resistances, which varied within a deviation of ±20% depending on the properties of the local soils. In the analyses, the total resistance gave a better correlation than the net resistance. Multiple correlations with two or three variables were found to predict the measured Vs (or G0) values more reliably than one-variable correlations. Accordingly, the BPT may be extended for geotechnical characterisation.