Evaluation of the efficiency of cone penetration test based design methods for determination of axial bearing capacity of piles

Prediction of axial capacity of piles has been quite a challenge due to many <involved uncertainties. Pile loading test is demanded to get a close prediction of the pile capacity. Cone Penetration Test, CPT, simulates the pile. It has been introduced in many researches for pile design. The output of these researches is wealth of design methods for determining the axial bearing capacity of piles.In many design methods, correlation coefficients are employed to cone data <to decrease the differences between pile and cone such as the scale effect. Yet, the design methods are diverse in accounting these coefficients in design. This diversity may question the suitability and applicability of the methods. Some soil affective conditions could generate during piling such as: strain softening, resistance degradation due to pile installation, sensitivity and dilatancy. The CPT design methods should consider the effect of these conditions. This research studies five CPT -based design methods. A documented database of sixty-eight case records has been collected to evaluate the methods. >Each case record includes the results of the static pile loading test, and CPT sounding performed at the pile location. The database has been categorized into >three soil groups: clay, sand, and mixed soil. The studied design methods were applied .tn.rletermine the axial pile capacity of. the case records. The thesis concentrates on clarifying the main requirements, advantages, and limitations of the studied design methods according to each soil group. Evaluation of the efficiency of the methods has been conducted through a <ranking procedure. The procedure is based on statistical and graphical criterions. Within the scope of this study and limited to the studied cases, CPT -based design methods are effective for designing the axially loaded piles. Bustamante andGianeselli is efficient for design in clay, while De Ruiter and Beringen is appropriate in sand. Introducing wide-range-parameters in the design equations, and applying one-to-one relation between cone resistance and unit pile capacity weakens the efficiency of performance of the CPT studied methods.