An integrated geotechnical database and GIS for 3D subsurface modelling: Application to Chennai City, India

Abstract

Subsurface characterization and clear distinction between layer boundaries in geological profiles are essential for successful completion of engineering projects. Due to limitations in accessing the vast and diverse subsurface information, efficient management of geotechnical data is of special importance. This study presents the methodology of building a digitally formatted and integrated spatial database using geotechnical data and geographic information system (GIS). The development of comprehensive geotechnical (geo)-database involves (1) Collection of borehole data from various reputed sources, (2) Validation of data in terms of accuracy and redundancy and (3) Standardizing and organizing the geotechnical information for incorporating into the database. The database is then integrated with GIS to provide the advantage of visualizing, analysing and interpreting the geotechnical information spatially. In addition, stratigraphic data stored within the spatial database is utilized for constructing three-dimensional (3D) subsurface models. A simplified approach is developed for 3D subsurface modelling with a combination of the Relational database management systems (Microsoft Access), Arc-GIS and Spatial interpolation techniques. The proposed methodology is illustrated using nearly 175 borehole data collected from various projects aimed at providing an exhaustive database and an integrated 3D environment for the Chennai City of south India for better interpretation and decision-making in regard to sustainable urban development. The study also demonstrates the application of the developed subsurface model in evaluating the effectiveness of multichannel analysis of surface wave (MASW) tests to estimate the depth to bedrock, which will be of immense use in foundation studies and in ground response analysis.