Geotechnical Section
National Geotechnical Borehole Database
The GSI has been making efforts to input all available site investigation reports, borehole and trial pit records to the national geotechnical borehole database, both for the Geotechnical viewer and the GeoUrban project. The Geotechnical viewer represents only one-sixth of the total number of investigations held for the whole country. Soil types and Depth to Bedrock (DTB) data is frequently recorded which contributes to revised quaternary mapping, Depth to Bedrock and Rockhead maps (available to view and query on the GeoUrban Viewer).
 
Revised rockhead of Dublin city, produced with ESRI Geostatistical Analyst

3D GeoModeller
3D GeoModeller (see 3D Modelling page) is a 3D geological modelling application which is being used to create bedrock and quaternary models as part of the GeoUrban project. The Geotechnical section has been concentrating on the input and modelling of borehole data in Dublin city. 



3D Geomodeller trials have been taking place in small areas of Dublin, particularly in the port area. Borehole records are selected from the National Geotechnical Borehole Database for an area. The geology is interpreted for each borehole using information contained in the logs and quaternary (unconsolidated sediments) maps of the area. This data is inputted into the GeoModeller software via Microsoft Excel records.

The image depicts boreholes in an area of approximately 800m by 830m in Dublin Port. The colours represent the different lithologies interpreted from the borehole logs/quaternary mapping (glacial tills, gravels, alluvium etc).

 
  

Boreholes can also be represented in 2D. An arbitary section can be drawn through any part of the data. Adjustments can be made to the stratigraphical layers if necessary and orientation values for each series can be added/updated.
  


The software computes and renders the geology according to the information provided in the borehole records and a DEM (digital terrain model). 3D surfaces such as in the image on the right can be produced.