Prediction of the Axial Capacity of Bored Piles Using Methods Based on CPT and Static Analysis Approaches

This study aims at evaluating the performance of five methods based on CPT and static analysis in predicting the axial capacity of bored piles installed in some Sudanese soils. These methods were used for estimating pile capacity at six study sites located in Khartoum and White Nile States. Static pile load tests and CPT soundings were performed at adjacent points in each site to enable comparison of measured and estimated data. Pile capacities were determined using the Van der Veen method of load test results interpretation. Statistical analysis was conducted to evaluate the performance of the five methods according to established ranking criteria. Based on the evaluation criteria adopted, Touma and Reese method showed the best performance by achieving the closest agreement between estimated and measured pile capacities whereas the Dutch method showed the lowest overall performance. From comparison of predicted and measured values of the pile end bearing (Qp) and skin friction (Q) capacity components obtained for an instrumented pile, the Touma and Reese method gave the best comparisons between measured Qp and Q whereas the Schmertman method showed a quite reasonable estimate of Q. The other three methods revealed unrealistic and gross over prediction or under-prediction of the two components of bored pile capacity.