Setting the standard for geophysical surveys in site investigation

Abstract

AbstractThis paper reviews the state of geophysics as applied to the engineering and environmental industries in the 1990s. The site investigation process is described emphasizing that inadequate attention is paid to understanding the ground in, or on, which structures are built. The basic principles of geophysical surveying are described, particularly the five major factors that influence the success of a geophysical survey: depth of penetration, vertical and lateral resolution, contrast in physical properties, signal to noise ratio and existing information about the site. The main surface, downhole and crosshole geophysical methods used in engineering and environmental investigations are discussed and illustrated with brief case histories from the literature. The integration of geophysical surveys into the site investigation process is described and a new procedure for the designing, commissioning and carrying out of a successful geophysical survey is presented. The underlying reasons why geophysics is perceived as ‘not working,’ are identified as a lack of understanding of both geological variability and geophysical methods on the part of the engineer and of engineering design and practice on the part of the geophysicist.