Shear Strength Evaluation of Lower Sand in Nakdong River Delta

An empirical method of estimating the shear strength of deep sands from the Nakdong River Delta was developed. The piezocone penetration test (CPT/CPTu) and sampling of disturbed sand at several depths were performed at two sites. A total of 39 isotropically consolidateddrained triaxial tests on reconstituted samples provided by a slurry displacement method were conducted to estimate the shear strengths. The sand deposits are classified into three types based on the physical properties and the soil behavior type index (Ic). The six existing empirical formulas considered in the present study, which are based on the overburden stress and cone resistance, either underestimate or overestimate the shear strengths of the sands obtained from the triaxial tests. By contrast, the newly developed empirical formula, which accounted for the types of sands in addition to the two other factors, matches well with the triaxial results.