Geotechnical investigation

Geotechnical investigations are very important before any structure can be built, ranging from a single house to a large warehouse, a multi-storey building, and infrastructure projects like bridges, high-speed rail, and metros.

Methods of observing the soils below the surface, obtaining samples, and determining physical properties of the soils and rocks include test pits, trenching (particularly for locating faults and slide planes), borings, and in situ tests.

These can also be used to identify contamination in soils prior to development in order to avoid negative environmental impacts.

Large-diameter borings are rarely used because of safety concerns and expense but are sometimes used to allow a geologist or an engineer to visually and manually examine the soil and rock stratigraphy in-situ.

Recommendations for the spacing and depth of investigations are presented in annex B.3 of Eurocode 7 - Geotechnical design - Part 2.

Specimens obtained by undisturbed method are used to determine the soil stratification, permeability, density, consolidation and other engineering characteristics.

In-situ gas tests can be carried out in the boreholes on completion and in probe holes made in the sides of the trial pits as part of the site investigation.

Geophysical methods are used in geotechnical investigations to evaluate a site's behavior in a seismic event.