Correlation of SPT-CPT Data from the Subsidence Area in Gölcük, Turkey

Abstract

Previous correlative studies The relationship between SPT N values and cone tip resistance q c , n = (q c /N) was analyzed by many authors. De Alencar Velloso [3] indicated ratios of SPT N values and cone tip resistance for different soil types and introduced 0.35 MPa for clay and silty clay, 0.2 MPa for sandy clay and silty clay, 0.35 MPa for sandy silt, 0.6 MPa for fine grained sand, and 1.0 MPa for sand. Meigh and Nixon [6] indicated that this relation did not consider the effect of grain size and recommended n-values as 0.2 MPa for coarse grained sand and 0.3-0.4 MPa for gravelly sand. Schmertman [9] called attention to the conversion of SPT data to cone penetrometer values if only SPT data are available. He recommended 0.2 MPa for silt, sandy silt, and slightly cohesive silt-sand mixture, 0.3-0.4 MPa for clean, fine to medium sand and slightly silty sand, 0.5-0.6 MPa for sandy gravel and gravel. He also suggested that the correlation of sleeve friction (f s ) with N values is better than that of q c and N value, especially for cohesive A correlation of standard penetration test (SPT) and cone penetration test (CPT) data was carried out by this study. The SPT provides information on the resistance and properties of soils and weathered rocks. In addition to the SPT, the CPT is widely used for site investigation and geotechnical design especially in alluvial areas, based on soil types. In order to determine the CPT values of the investigation areas, where only reliable SPT values are available, the SPT blow counts (N values) can be converted into CPT cone resistances (q c values) by an SPT-CPT correlation. The correlation of SPT-CPT test results from the subsidence area was performed using statistical methods. The soils in this area are recent alluvial deposits, consisting mainly of silty clay, clayey silt, clay and sandy clay. The qc values are not increased when SPT values are increased as it is expected.