Pile response and free field vibrations due to low strain dynamic loading

This paper presents the results of in situ measurements during dynamic pile testing at a construction site in Louvain-la-Neuve. Main objectives are the investigation of the pile response and the free field vibrations due to low strain dynamic loading on a single cast in situ pile with a 5.5 kg hammer impact on the pile head. Whereas low strain testing is usually performed to assess the integrity of the pile as a structural member, this study focuses on both pile and ground vibrations. The pile head response and ground motions are measured with accelerometers during different blows with the impact hammer. The dynamic characteristics of the soil are determined with a SASW test. Experimental results are compared with predictions obtained with a coupled finite element–boundary element model. The computed pile head and free field response show a good correspondence with the measured response. In addition, the static stiffness of the pile estimated by means of the mobility function shows a very good agreement with the value calculated by an analytical formulation.