Ground vibrations due to pile and sheet pile driving : influencing factors, predictions and measurements

Abstract: Ground vibrations due to pile driving are part of a complex process. Vibration is generated from the pile driver to the pile. As the pile interacts with the surrounding soil, vibrations are transferred at the pile-soil interface. The vibration propagates through the ground and interacts with structures, both above ground and underground. The vibration continues into the structure where it may disturb occupants and/or damage the structure.In this thesis the study of the vibration transfer process due to pile driving is limited to the vibration source and the wave propagation in the soil. Vibration transmission to adjacent buildings and structures is not studied. However, impact of vibrations on buildings is briefly discussed in the literature study.It is important to accurately predict the magnitude of ground vibrations that result from pile driving in urban areas, both over- and underestimated vibration levels lead to increased costs. A lot of research has been performed within this field of knowledge, but a reliable and acknowledged prediction model for vibrations induced by pile or sheet pile driving is still needed.The objective of the research project is to increase the knowledge and understanding in the field of ground vibrations due to impact and vibratory driving of piles and sheet piles. This research project also aims to develop a reliable prediction model that can be used by practising engineers to estimate vibration due to pile driving. This licentiate thesis presents the first part of the research project and aims to increase the knowledge and understanding of the subject and to form a basis for continued research work.The most important findings and conclusions from this study are:The main factors influencing vibrations due to pile and sheet pile driving are; (1) the vibrations transferred from the pile to the soil, (2) the geotechnical conditions at the site and (3) the distance from the source.The vibrations transmitted from the pile to the soil depend on the vibrations transferred to the pile from the hammer, the pile-soil interaction and the wave propagation and attenuation in the plastic/elasto-plastic zone closest to the pile.There is today no prediction model that fulfils the criteria of the “perfect” prediction model; reliable but yet easy to apply.Future research should study the transfer of vibrations at the pile-soil interface, including the generation of a plastic/elasto-plastic zone in the area closest to the pile and how that affects the transfer of vibrations from the pile to the soil.

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