Computer analysis of stress waves in driven piles

The propagation and reflection of stress waves in piles due to the driving action are investigated. Mindlin-Herrmann equations, which include the Poisson effect, are used to model the pile. The hammer blow on the pile can be prescribed in the form of stress, strain, velocity or acceleration boundary conditions. The analysis is based on the concept of a wave as a carrier of discontinuities in the field variables and their derivatives. These discontinuities are determined from a set of recurrence relations which are in turn generated by the use of time harmonic asymptotic series solutions to the equations of motion. Stress concentrations in the pile due to wave reflections are treated. The analysis is easily programmed and numerical examples are presented to illustrate the method of solution. The results indicate the distortion of the stress waves, which has the beneficial effect of reducing the duration of possible stress concentrations in the pile. Stress waves due to other boundary conditions at the pile ends can be treated by using the results presented herein.