Abstract：The blocky soil samples with 250 mm diameter have been proved to be of superior quality compared even with the soil samples of thin-wall piston with 75 mm diameter. Therefore triaxial and oedometer tests on the blocky soil samples can give the best reference parameters for correlation to CPTU measurements. A new generation of correlation factors among CPTU parameters，undrained shear strength，pre-consolidation stress and over-consolidation ratios are developed for soft clays. It is the authors’ opinion that for important projects a combination of CPTU tests and blocky soil samples will give reliable design parameters leading to significant cost savings.
