Determination of confined compression modulus of soft clay using piezocone penetration tests

The existing interpretation methods for piezocone penetration tests (CPTU) are reviewed for prediction of the constrained compression modulus (E_s). Three expressway sites in Jiangsu Province are selected for this study. In each site, CPTU tests are performed supplemented by consolidation tests using high-quality undisturbed soft soil samples. Then, E_s-predicted methods based on the CPTU tests are compared and evaluated. The new correlations are also developed to predict the values of E_s from the cone tip resistance (q_c), corrected cone tip resistance (q_t) and net cone tip resistance (q_n) for soft clay in Jiangsu Province. Furthermore, the correlations are verified by comparing the total settlements predicted from CPTU and the measured settlements for one selected expressway site. The results show that the Senneset et al（1989）method based on the net cone resistance is able to predict E_s better than the other methods. The predicted total settlements based on CPTU parameters show a better agreement with the measured ones. Accordingly, the reliability of the application of CPTU for E_s and settlement prediction is verified.