Static and dynamic behavior of laterally loaded single piles and determination of P-y curves

To improve the understanding of soil-pile interaction under horizontal dynamic loads and seismic events, a parametric centrifugal study was undertaken. Flexible piles with pile caps of different masses and instrumented with 20 strain gauges on the length of the pile were used for this purpose. The piles were impacted and the resulting displacement and acceleration for different levels of force were measured. The equation of the movement of a beam equivalent to the pile under dynamic loading has been established and all the terms of this equation was determined using the experimental results. The term of inertia was divided into two parts, one related to the mass of the pile and the other related to the mass of the associated soil. The contribution of each term to the equation at different period (or time of) of vibration was illustrated. Distribution versus time of the displacements and the reactions of the soil at any depth were deduced from the profiles of the bending moments by a double integration and a double derivation respectively. Then the dynamic P-y curves or loops were constructed based on these results. The procedures of experimental tests and P-y curves construction are explained and a comparison between static and dynamic P-y curves is also indicated.