A new standard in the practice of engineering seismic refraction

• Published in: Modern Geophysics in Engineering Geology Vol. 12; pp. 391 - 398
• Main Authors: Walker, C. S., Win, M. A.
• Format: Book Chapter
• Language: English
• Published: The Geological Society of London 01.01.1997; Geological Society of London
• Series: Geological Society, London, Engineering Geology Special Publications
• Subjects: Earth Sciences; Geophysics, Geodesy & Seismology
• ISBN: 1897799926; 9781897799925
• ISSN: 0267-9914; 2041-4730
• DOI: 10.1144/GSL.ENG.1997.012.01.37

Seismic refraction is applied routinely to all stages of highway engineering projects in Australia and is particularly useful for investigation, design and contract documentation of road cuttings. The Roads and Traffic Authority of NSW (Australia) has developed a new standard of practice in seismic refraction since the late 1980s. The most significant advance has been to reduce shot spacing. This means that high levels of reversed coverage of all refractors and high levels of data redundancy are achieved, ensuring a well controlled interpretation with much reduced ambiguity. Other important advances are more efficient and rigorous equipment and field procedures, greater attention to data quality, PC based interpretation and improvements in reporting and documentation. The seismic information is now an important component, together with geological information, in the development of a geological model of a site. Previously, particularly in complex weathered and fractured terrains, the seismic information was not regarded as reliable enough for this purpose. The result of these advances is that seismic refraction surveys cost the same or less per km as ten years ago but produce more detailed and reliable information. The benefits are better information for design, more reliable information for construction tendering and reduced incidence and cost of contractual claims. This paper discusses in detail the new standard in seismic refraction practice and presents a field example.