Reliability assessment of CPTU-based pile capacity predictions in soft clay deposits

This paper focuses on the piezocone (CPTU) test results and the related interpretation procedures to predict ultimate pile load capacities of driven and jacked piles for the Jiangsu soft soil deposits in China. The pile foundation data including pile load tests on twenty six piles from several field sites are compiled and presented. A comparison was made to explain the advantages and fallacies of various CPT based interpretation methods. A modified CPTU-based method has been proposed, which was used to predict the ultimate capacity from effective cone tip resistance and excess pore water pressure. Comparison of the calculated pile capacities to the measured pile capacities showed that the modified CPTU method's predictions showed a better agreement with the ultimate load capacities determined from static loading tests. Also, there was less scatter in this method's predictions than other CPTU methods for deep foundations of soft clay deposits, indicating a higher reliability in the proposed methodology.

► A modified CPTU-based method was proposed to predict the pile ultimate capacity.
► The method can take into account effective cone resistance and pore pressure.
► The modified method showed a better agreement with the static loading tests.
► There was a higher reliability in the proposed methodology than other methods..