Evaluation of CPT-based characterization methods for loose to medium-dense sands

As a result of the difficulties related to obtaining undisturbed samples of cohesionless soils, CPT-based empirical correlations, often developed from calibration chamber experiments, are widely used for determining many soil parameters for geotechnical investigation. This paper describes the application of 19 reduced-scale calibration chamber cone penetration tests to evaluate empirical correlations for predicting the relative density, the unit weight, the constrained modulus, and the soil identification of loose to medium-dense sands. A subtraction cone, 6 mm in diameter with an apex angle of 60° and a net area ratio of 0.75, is used in the laboratory tests. Due to the fine gradation of the quartz sand used in the experiments, some of the CPT results are located within the silty sand range of the soil identification charts. An extensive evaluation is also presented for the stress normalization process of the CPT data. It is determined that a relative density-based overburden stress normalization method provided the best estimates for correcting the cone tip resistance for effective overburden stress.