DETERMINATION OF DRAINED FRICTION ANGLE OF SANDS FROM CPT

Existing methods commonly used for determining drained angles of the i nternal friction of sands using cone penetration test (CPT) data are e xamined and interpreted in this paper, with emphasis on the influence of the compressibility of sands. The methods examined are based either on the bearing-capacity theory or on the cavity-expansion theory. Thi s paper emphasizes the development of an empirical approach, based on the cavity-expansion theory, for determining the drained friction angl e of sands from CPT data. To this end, a new empirical correlation for determining the volumetric strain, which is required in the Vesic met hod for determining the drained friction angle, is developed through c alibrations with methods based on the bearing-capacity theory. Using t his new empirical correlation, the volumetric strain can be obtained s olely from CPT data without additional laboratory tests such as the tr iaxial test. Field CPT data are used to examine and demonstrate the ne w approach, and the results show that the drained friction angle can b e consistently determined using this approach.