In Situ Geotechnical Investigations

Abstract

The geological environment is in continuous evolution due to natural processes that can be accelerated by anthropogenic activities. The uncertainty associated with estimating the properties of the ground has a relevant impact on the design and mainly on construction safety. Poor site investigations and savings on the budget for the ground studies have proved to be false economies, causing increased costs and time overruns on the ground design and construction projects. The extent and depth of the investigation required for any project depend on several factors, namely, the type, dimensions, and location of the construction (e.g., at the surface or underground, urban or rural), geologic and geomechanical conditions, geological hazards and the site’s features or characteristics. A comprehensive program of site investigation includes engineering geological mapping at an adequate scale, the use of indirect (geophysical techniques) and direct methods (boreholes and excavation techniques), as well as in situ tests in soils and rock masses. Although most of these methods have been created at the beginning of the twentieth century, they have evolved dramatically in the last decades to comply with the challenges of larger and complex constructions and the development of information technologies. The present chapter reviews the state of the art regarding site investigation methods, their applicability and objectives. It highlights the main achievements in the last decades and their response to increasingly demanding engineering works.