Foundation Evaluation of a Barrage using Geophysical and Geotechnical Investigations
Proceedings of the conference on Recent Advances in Rock Engineering (RARE 2016)
Geophysical investigations prior to constructions stage are often met with difficult site conditions particularly over shallow water bodies. Due to site constraints, standard data acquisition procedures, either onshore or offshore may not be suitable in such cases. In this situation designing of site specific investigation technique becomes necessary to explore the subsurface condition. In one such case study for locating the barrage axis with rockmass in the foundation, seismic refraction
... mic refraction survey was deployed. The survey data was acquired both onland and onwater-body to map the bed rock depth and geological features in the study area. A combined section was then obtained by joining lines on surface and over waterbody.Based on data processing, the subsurface layers wereclassified as compact soil, weathered rockmass layer with boulders, jointed rockmass layer and hard rock layer based on the seismic velocity range. These results were correlated with the available data on geological situation, Standard Penetration Test (SPT) values and laboratory studies. Interpretation of survey data hinted at the shifting of river course away from the left bank by at least by 50-60m. Considering the site conditions, it was suggested that the left bank abutment may be extended by 30m for coupling with the in-situ hard rock.