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Abstract
Recent development for capacity evaluation of the bered and drilled piles is the Osterberg cell or O-cell terst. The O-cell is placed just above the pile base. or at a special distance above the base of the pile, to produce two equal and opposite forces. One force is acting downward on the pile base, and the other force is acting upward on the pile shaft.
In this study, the Psterberg test model is carried experimentally at the laboratory on bored piles embedded in sandy soil. Four different diameters for piles are tested using sand with different relative densities. Also, all piles are tested using conventional pile test method.
Different methods for extrapolation such as Recommendation method and Decourt method of the downward load-displacement curve of the pile base are presented. Generally, in most cases of the pile foundation, the friction load is smallar than the base load.
The present research shows thae pile load-settlement relationship and pile-soil stiffness obtained from two methods Osterbrg cell and conventional load test of pile testing are compard. Values of the bearing capacity coefficient (Na) obtained from the tests are compared with their values obtained from the Egyptian code of soil mechanics and foundation design.
To verify the experimental study, numerical analysis using axisymmetrical finite element model is used to study the load-displacement relationship and are compard with the experimental results obtained using O-cell test. The analysis is carried out using PLAXIS program. Sandy soil is represented by Mohr Coulomb yield criteria. The used parameters in the numerical model are taken from the experiments carried out on sandy soil. A wide range of results can be obtained from the numerical analysis such as total and effective stresses in soil, shear stresses in soil, skin friction distribution on the pile surface, stress distributions at the pile base in the soil can also be obtained.