Determination of soft clay parameters from CPTU tests, the FINCONE test sites revisited

The CPTU test offers the possibility of continuous and reliable measurements of three independent readings, namely cone tip resistance ( q c ), sleeve friction ( f s ), and penetration porewater pressure at the shoulder ( u 2 ), which can then be used to derive various soil parameters. The article presents a new approach for the determination of preconsolidation pressure ( σ p ′), undrained shear strength ( s u ), and constrained modulus for the over-consolidated region M 0 . The preconsolidation pressure is derived from net tip resistance q net , excess pore pressure Δ u, and effective tip resistance q eff using nonlinear functions based on the pore pressure parameter B q . Well-established transformation models are then utilized to derive s u and M 0 from σ p ′. The proposed transformation models proved to work well for all tested data irrespective of the sensitivity of the clay. They also provided better prediction performance compared to previous, partly more site-specific solutions. In addition, the three independent solutions using either q net , Δ u, or q eff gave very consistent solutions giving almost equal depth-wise predictions.