An MASW survey for geotechnical engineering in an urban setting - an application to pre-tunnelling investigation.

Abstract

As a part of the Airport Tunnel project, an MASW survey was carried out to investigate the nature of the fill site of an old rock quarry. The site is currently used as a shopping centre car park in an inner suburb of Brisbane along one of the main roads. To avoid excessive noise, the survey took place at night. The MASW is a surface wave seismic method, particularly suited to characterisation of the near-surface. Some part of the seismic data presented an unusual but consistent noise pattern. The analysis of the seismic data outlined the depth and shape of the quarry. The noisy area was identified as a shallow hard rock left in the quarry, perhaps as an access ramp. This was verified a historic photography of the old quarry. The depth of the quarry was found shallower than the proposed depth of the tunnel to ensure the safety of boring.