CORRELATION OF THE TEXAS CONE PENETROMETER TEST N-VALUE WITH SOIL SHEAR STRENGTH

Improved correlations have been developed between the Texas Cone Penetrometer Test N-value and the shear strength of both cohesive and cohesionless soils. Correlations were also developed and compared with existing correlations for several shear strength parameters and the Standard Penetration Test N-value. Both field and laboratory investigations were conducted to obtain the necessary data to develop the correlations. Penetrometer test data and undisturbed soil samples were obtained from five test sites for cohesive soils and six test sites for cohesionless soils. Reasonably good correlations were developed between the unconsolidated-undrained shear strength and the penetrometer test N-value for cohesive soils including homogeneous clays of high plasticity and silty or sandy clays of low plasticity. In addition, a reasonably good correlation was developed between the drained shear strength and the penetrometer test N-value for cohensionless soils including poorly graded sands and silty sands. The currently used relationship between the effective angle of shearing resistance of cohesionless soils and the penetrometer test N-value was found to be a lower bound for the data obtained in this study. Finally, correlations were attempted between unit skin friction and unit point bearing obtained from bored and driven pile tests and the penetrometer test N-value. These correlations are considered preliminary because only a limited amount of data was available from the instrumented pile load tests. /FHWA/