COMPARISON OF VANE SHEAR AND FALL CONE STRENGTHS OF SOFT MARINE CLAY

A total of 1,014 measures of sediment shear strengths were measured by means of miniature vane shear and fall cone tests on five gravity cor es collected in Eckernfoerde Bay, Baltic Sea. Paired t test was used t o compare the shear strengths measured by the two methods. It was foun d that fall cone strength calculated with Wood's K-60 value (0.29) ove restimates the vane shear strength by 0.15 kPa (alpha = 0.001) and the sample mean of the fall cone strength is 4.1% higher than the mean of the vane shear strength. However, fall cone strength calculated with Hansbo's K-60 value (0.24) underestimates the vane shear strength by 0 .88 kPa (alpha = 0.001), and the sample mean of the fall cone strength is 13.8% less than the mean of the vane shear strength. Both calculat ed fall cone strengths are significantly different from the vane shear strength with a p value of less than 0.001. Regression analysis of th e Echernfoerde Bay data indicates that a new K-60 value is 0.275 with a confidence interval (alpha = 0.01) from 0.2704 to 0.2786. Paired t t est shows that there is no significant difference between miniature va ne shear and fall cone tests for these samples if the fall cone streng th is calculated with K-60 = 0.275.