Chapter 13: The ground profile and its genesis

A ground profile, or vertical profile, is the starting place for developing an understanding of the ground for design, analyses and construction. It is a record of the ground at depth and an interpretation of its formation up to the present. The correct identification of the materials within a profile and interpretation of their history indicates how ground is likely to respond to changes arising from construction or from natural processes such as rainfall and earthquakes. Decisions based on a profile that is incorrect are unlikely to be corrected later by subsequent calculations, no matter how sophisticated these calculations may be, because they will be quantifying something that does not exist. Mistakes made with the ground profile can delay works and even stop contracts and may result in claims. Profiles enable cross-sections to be constructed and these are the templates upon which the distribution and magnitude of all other geotechnical data should be superimposed. That is the surest way to obtain a relationship between the geotechnical properties for the materials present and their geology: many case histories demonstrate this. Case histories are part of the inherited wisdom of geotechnical engineering and remove any excuse for either ignoring a ground profile or for obtaining one but failing to use it appropriately in design and construction.