Unit skin friction from the extended dynamic cone penetrometer (EDCP) test supplemented by measurement of torque within testing wells



The Extended Dynamic Cone Penetration (EDCP) test supplemented by measurement of torque (EDCP-T) may be used to obtain a direct measurement of unit skin friction (fs) between the cone section and the surrounding soil. The test is performed after completion of the EDCP test. In order to perform the EDCP-T, the EDCP device is rotated after driving the rod and maximum torque is measured using a calibrated torque wrench that is connected to the top of the EDCP. The EDCP-T test results at 3 sites are presented. The results show that the unit skin friction values obtained from the EDCP-T generally correlate well with normalized blows for 30 cm penetration of the EDCP tip (NEDCP(n)). The results may be valuable for preliminary estimation of unit skin friction of the driven piles.