Investigation of Non-Uniform Pile Behaviour Under Torsional Harmonic Vibration

Pile foundations for machines and structures are often subjected to horizontal or vertical harmonic vibrations. However, in some situations, piles also experience torsional harmonic vibrations. While there are some research work on tapered piles imposed to horizontal or vertical harmonic vibrations, the response of such piles till now is lacking. In this study, the elasto-dynamic theory has been used to derive the governing differential equation on a tapered pile experiencing torsional harmonic vibration. In this approach, the pile is assumed the pile has circular cross sectional area and consists of elastic material. It is further assumed that there is sufficient connection between the pile and the soil, so that the slippage cannot occur at the pile-soil contact surface. By using the developed method, the effect on the pile dynamic torsion amplitudes of the taper angle has been investigated. It has been found that the twist angle of the pile decreases with increasing the taper angle while the length and volume of the pile is kept constant. This reveals that the use of tapered piles leads to a better performance for foundations compared with the case of using straight-sided piles of the same length and volume