Dynamic Response of Batter Piles

Abstract eng:
Batter or raked piles have been used, especially in offshore structures, bridges, and towers to resist large lateral loads generated due to winds, tidal waves, soil pressure etc. From the past experience, the performance of batter piles were found poor for seismic resistance, resulting in bad reputation. In some cases, the key reason for the poor performance of batter piles was due to large shear force and moment induced at the pile head. Many researchers also suggested to avoid the use of batter piles in seismic prone areas, due to subsequent poor performance of batter piles during earthquakes. Several codes also recommends to avoid batter piles in moderate to severe seismic prone area. Various attempts have been made by engineers and researchers to improve the seismic performance of batter piles and to modify the existing design strategies to overcome these problems. Past studies also showed that the use of batter and vertical piles together in a pile-soil system increases its overall efficiency. Researchers also reported that in particular cases, the use of batter pile groups is advantageous in supporting lateral loading. The emphasis of this study is to understand the dynamic lateral behavior of single batter piles under machine induced vibrations. The piles are excited in both horizontal directions, (viz., along batter and across batter). To simulate the vertical and batter piles, 3D dynamic implicit Finite Element Analyses were carried out using ABAQUS (with state-of-art pre and post processor). Soil mass, pile, pile cap and machine were modelled using 4-node linear tetrahedron element (C3D4). Lateral soil boundary has been simulated after performing the sensitivity analysis for soil mass. Soil pile interaction has been taken into account in terms of tangential and normal contact properties at the soil pile interface. Separation of soil mass has been allowed at the normal contact interface. Parametric study has been performed considering different pile inclinations (i.e. 10˚ and 20˚ from the vertical) and varying force levels of excitation (with varying excitation frequency and eccentricity of the oscillator). Responses of vertical and batter piles were estimated in terms of lateral displacement at the pile cap. This study shows that batter piles have performed very well than the vertical pile under moderate to heavy machine induced vibrations. Hence, batter piles with critical inclination significantly improve the performance of foundations subjected to lateral loads.

• Export as: BibTeX | MARC | MARCXML | DC | EndNote | NLM | RefWorks
• Add to your basket