CPT-Based Approach to Study the Load-Displacement Behavior of Driven Piles by the New Method of Stress Characteristics

In view of principles of the theory of plasticity, the stress field is not independent of the displacement and/or deformation fields. Therefore, a more reliable analysis will be achieved if the bearing capacity and load-displacement behavior of piles are analyzed simultaneously. In this study, a new analytical-numerical method has been proposed to estimate the bearing capacity and axial load-displacement behavior of driven piles in granular soils using CPT records. For this purpose, the method of stress characteristics is used to analyze the stress field below and around the pile and in effect, the failure mechanism. This failure mechanism is then used by implementation of the kinematical approach of the limit analysis to compute the displacement field. This procedure is employed in a step-wise manner to gradually calculate the stress and displacement field as the pile is assumed to penetrate into the ground. One should note that the mobilization of the friction angle is linked to the gradual increase in shear strains in the field. This is done by making use of the CPT results which are both continuous and reliable in comparison to standard laboratory tests often conducted on disturbed samples at discrete intervals. Hence, the step-wise procedure is expected to give rise to a complete load-displacement behavior of driven piles shown in a practical case.