Application of EPS geofoam in attenuating ground vibrations due to vibratory pile driving

Keynote Lecture 1: Modern day urban construction activities are largely carried out adjacent to existing buildings due to scarcity of land for construction. In order to utilise the available land in the most efficient way, often high-rise buildings are constructed necessitating pile foundations to transfer large design loads to strong and deep soil layers below the ground surface. Although a number of methods are available to install pile foundations, in urban areas several factors need to be taken into consideration when selecting the suitable method. Due to the proximity of new and existing structures, noise disturbance and damages to existing nearby structures resulting from pile installation should be kept to a minimum. In that respect, vibratory pile driving is the most suitable pile installation method for urban construction activities. However, ground vibrations induced by vibratory pile driving may cause damages to existing structures depending on the proximity and sensitivity of the structure. Hence, it is necessary to take proper mitigation measures against vibratory pile driving induced ground vibrations. A possible remedy is to use in-filled wave barriers with concrete, bentonite, water or expanded polystyrene (EPS) geofoam, which can diminish the construction induced vibrations. EPS geofoam offers a number of advantages over other fill materials because of its light weight, cost effectiveness, energy absorbing characteristics, efficiency in terms of construction time and ease of handling. There have been many research studies carried out to investigate the mechanical behaviour of EPS geofoam. However, the full potential of EPS geofoam is yet to be realised. Therefore this thesis aims to investigate the severity of ground vibrations induced by vibratory pile driving and effectiveness of EPS geofoam wave barriers in protecting nearby structures. These investigations are carried out using both two- and three-dimensional finite element models developed based on the Arbitrary-Lagrangian-Eulerian approach. They are discretised in both space and time to capture the wave propagation within ground