Evaluation of Relative Density and Shear Strength of Sands from CPT and DMT

The paper summarises the experience gained by the writers in the interpretation of the cone penetration test (CPT) and flat dilatometer test (DMT) for the assessment of the geotechnical properties of sands. In the first part of the paper, the problem of determining the relative density (D_R) as function of the penetration test results and ambient stress (σ'), for silica sands, is dealt with. In the second part of the paper, the assessment of the peak angle of shearing resistance (φ'_p) is dealt with. The attention is given to the use of the Bolton's strength-dilatancy theory in order to estimate φ'_p. Engineering correlations, based on Bolton's work, are proposed allowing estimation of φ'_p as function of penetration resistance and σ', taking into account the compressibility and the curvilinear shear strength envelope.