A site investigation covers three stages, a preliminary appreciation of the site, a ground investigation in which borings and laboratory testing are undertaken, and a final stage in which the conclusions of the ground investigation are checked against the actual ground conditions as revealed by the constructional excavations. This paper considers the planning and implementation of the ground investigation under conditions normally prevailing in the British Isles.
Various procedures are described for boring in soils and rocks, for trial excavations, for probing, and for geophysical surveying. Sampling procedures are considered on the basis of the quality of the sample thus obtained. Sample quality ranges between almost fully-undisturbed soil samples as taken by a thin-wall piston sampler, and fully disturbed samples taken from the drill tools.
The choice of procedure for boring and sampling is determined by the technical requirements of the investigation, by the practical problems arising from site conditions and by economy. It is considered that investigations should start using standard equipment and that the more sophisticated and expensive procedures should be employed only when the nature of the geotechnical problem has been determined.
The paper concludes with a discussion of the management and organization of site investigations.