A Modification of Pile Unit Skin (f) of Frictional Resistance (Qs) on Clayey Layer at Central of Jakarta

: The evaluation of pile unit skin friction (f) is important and difficult in determining frictional resistance (Q s ) of single pile. A modification was conducted on curves and table design of (f) in clayey soil from Nottingham & Schmertmann and Schmertmann methods. PDA test was used as the valid data to compare the prediction analysis result using these methods. Resistance friction (Q s(u) ) and (Q s(Ru) ), respectively of single pile were obtained by 5 random points of CPT analyzed by Schmertmann methods and 2 points of PDA test evaluated by CASE and CAPWAP methods from study site. From the result of modification of unit skin friction analysis using CPT data approaching to the real data from PDA test results.