Seismic refraction tomography using underwater and land based seismic data for evaluation of foundation of civil structures

• Published in: Journal of applied geophysics 2023-03, Vol.210, p.104934, Article 104934
• Main Authors: Butchibabu, B., Jha, P.C., Sandeep, N., Sivaram, Y.V.
• Format: Article
• Language: English
• Subjects: Foundation evaluation; Seismic refraction tomography; Standard penetration test, Bed rock, P-wave velocity
• ISSN: 0926-9851; 1879-1859
• DOI: 10.1016/j.jappgeo.2023.104934

Inadequate subsurface information around the proposed structure often leads to disruptions to the plan of construction, resulting in delays in the implementation of design, and finally hampering the progress of the work. Therefore, geophysical and geotechnical investigations prior to any civil construction should be adopted to characterize the rock mass conditions at a given site. Quick results on engineering evaluation of sites are imminent due to tight timelines and when site conditions do not favor readily deployable testing methods. Suitable tailor-made acquisition techniques need to be adopted to arrive at the best evaluation possibility. Two such cases are discussed here, wherein one site had proposed barrage alignment, abandoned after laying foundations for four pillars and in the second site, foundation of three pillars of a road bridge was unexpectedly met with poor rock conditions. In order to investigate and evaluate the foundation rock conditions, Seismic Refraction (SR) survey was carried out in both the cases. SR data were acquired using tailor-made array across the river using hydrophones and geophones on water and land respectively. This paper discusses the pragmatic approach in data acquisition for the given site conditions along with the pertinent data processing using Seismic Refraction Tomography (SRT) technique, analysis, interpretation of the results correlated with the geotechnical data at the same site. The outcome of the investigations and the benefits of the pragmatic approach for evaluation of foundation in such cases are aided in design modifications of the proposed civil structures. •Properly planned geophysical investigations reduces cost over runs and project delays.•Prior mapping of subsurface features is vulnerable.•Bed rock detection using seismic refraction tomography.•Delineation of paleo-river course.•Geophysical mapping suggests remedial measures.