A Cartiometrically Orientated Geotechnical Database for the Birmingham Area

Abstract

A study of the potential users of an urban geotechnical map reveals that they could all utilise the same, existing information - if it were capable of presentation in different forms. A suitable multiuser, multiparametric, three dimensional, engineering geological map can be generated, stored and manipulated on an interactive computer. In order to save storage space, improve the spatial distribution and minimise : sampling errors the data (site investigation reports; general... records, maps and machine readable information) are pre-processed onto a square grid which is chosen to match the data: distribution of the mapped area. After an analysis of the possible locations and facilities, the system is written for a Harris 500 minicomputer. The data are stored as numeric equivalent codes and integerised real variables packed onto hierarchical, magnetic disc, direct access files. Routines are written in FORTRAN 66 (using GINO-F and a raster control library). Output formats are maps, sections and single archetypal boreholes, based on a (minimum) resolution of the 100m square 'segment'. Vector and raster graphical techniques are developed for conversational displays of geological information. These displays may be shown on VDU screens, X-Y plotters and printers. The datastore creation process is examined and recommendations are made for its improvement. A user's manual for the 'map' is included, as are detailed descriptions of the programs and datastructure. The use of the database in the controlled interpolation of a three dimensional model and the production of a set of new maps (including an enhanced rockhead surface and a hazard map) is described. The advantages, disadvantages and potential of this spatial information system are reviewed and the possibility of transfer to a microcomputer is discussed.