Piling Vibration Measurement
Xi Engineering use finite element modelling to predict the amplitude of vibration at nearby sensitive receptors, related to both impact piling and vibro-piling. Xi also provide geophones for the long-term measurement of ground-borne vibration to determine whether vibration has breached pre-defined limits.
The finite element method involves generating a 3D finite element (FE) model of the piling source, the layered ground and the assessment locations. An FE model takes into account the actual geometry and material properties of the ground based on geotechnical reports and computes the velocity at several previously selected elements, in particular at locations representing the assessment locations. In the case of impact piling the FE model is solved in the time domain to determine the peak particle velocities (PPV) at the selected sites. In the case of vibro-pile the PPV is assessed by solving the model in the frequency domain for any given hammering frequency. The modelling results can then be compared to the statutory requirements, for example BRE Digest 403 Assessment Criteria, for any given region and risk of breaching the criteria assessed. In the event that a breach is likely, Xi can use this modelling approach to recommend mitigation methods.
Acoustic ray tracing techniques may be used to assess the impact of noise on local residents. These take into account, topography, the surrounding infrastructure and ambient noise levels. If it is likely that noise levels could breach local standards, Xi can use this modelling approach to suggest mitigation strategies and determine their effectiveness.