Compaction evolution observed via the HVSR of microtremors

The non-invasive measurement of horizontal to vertical spectral ratio (HVSR) of microtremors is proposed as a means to evaluate field compaction. The HVSR technique is a surface wave method that is quite distinct from the class of array-based surface wave techniques. This is because the basis of the former is the recording and fitting of the HVSR of microtremors, while the latter relies on the recording and fitting of the surface wave velocity dispersion curves of ground vibrations. This paper presents a controlled study of the evolution of compaction, showing it is possible to identify levels of field compaction by observing changes in HVSR data. The results from this study suggest that the fast and operationally simple HVSR technique could be used to assess near-surface ground compaction. It is further envisaged that the technique could be applied to ‘cover the gaps’ left from traditional and expensive invasive techniques (e.g. cone penetration test, standard penetration test, dilatometer test, etc.), particularly for extensive and deep-filled areas such as would occur in dynamically compacted sites.