Dynamic analyses of pile driving
Several approaches to the dynamic analyses of pile driving are explored in this Thesis. These include pile driving formulae, single degree of freedom (SDOF) models, the wave equation approach and a finite element model. In the elementary models, the pile is modelled as a rigid mass while the soil is represented by various simple rheological mechanisms (spring-slider-dashpot models). Analytical and numerical formulations are developed and the parametric results of the analyses are presented in non-dimensional form. A study of the wave equation method of the analysis culminates in the development of some simple analytical expressions (analogous to the pile driving formulae) which may prove useful in practice. Some comparisons between the elementary SDOF models, the pile driving formulae and the wave equation have been undertaken in order to assess their strengths and highlight their various shortcomings. The development of a finite element model for pile driving is discussed in detail with particular emphasis on spatial discretisation (especially the viscous boundaries) and the time integration schemes. A limited parametric study has been conducted in order to gain some insight into the behaviour of piles during driving and to follow the evolution of failure in soils around and beneath the piles. Further work in this area is indicated although computational costs seem to be too high to justify use of the finite element method.