The Differences Between Soil Investigation and Geotechnical Drilling
by Nate Vickery on August 08, 2017

To a layman, constructing a building might seem as simple as picking out an empty piece of land, and erecting a concrete rectangle in a matter of months. As you might have guessed, the science about soil and investigation, drilling, and construction is far more complex than you might have initially thought.

The process of geotechnical drilling is quite different from soil investigation itself, although both processes play a crucial role in any construction work and form a basis of every building project. Here are the key differences you need to know before venturing into a construction process in order to achieve the best possible results.





Soil investigation

Soil investigation, also known as geotechnical investigation, is used to assess the type and state of soil in a particular area, its surface and inner composition, and is usually conducted by engineering geologists using numerous contemporary methods. Unlike geotechnical drilling, soil investigation aims to obtain invaluable information on the physical properties of soil mostly through non-invasive methods, although drilling is often required to further assess the area.

Moreover, soil investigation aims to measure the thermal resistivity of soil or backfill materials required for oil and gas pipelines, radioactive waste disposal, and solar thermal storage facilities as well as underground transmission lines. If a subsurface investigation of soil is needed, engineers will use one or more techniques to extract a soil sample and determine its physical properties in a laboratory.

For these purposes, engineers can use boreholes, trial pitting, in-situ testing and dynamics probe testing as well as other invasive or non-invasive techniques.

Lastly, soil samples can be categorized as disturbed or undisturbed. Disturbed samples have an altered structure, which will be accurately determined by structural tests assessing the properties of soil grains.

Conversely, undisturbed samples have properties that are similar to those of the soil in its original setting, and allow tests of structural properties to be used to approximate the contents of the soil in its original state.

Geotechnical drilling

Geotechnical drilling is a type of drilling intended to provide the contractor with the necessary information regarding the soil, prior to beginning the construction process. The process is mostly used for buildings, oil rigs and houses. Professional drilling contractors usually conduct this type of projects, as they need to be qualified to operate specialized equipment.

A geotechnical engineer will supervise the procedure in order to ensure that the drilling meets all of the project requirements and that it is conducted in compliance with all applicable state and country laws and regulations. The best geotechnical drilling contractors will also provide supplementary services, such as non-invasive soil investigation, depending on the size and location of the project.

The type of drilling equipment used to perform the work will vary greatly, according to the size, scope, soil type and location of the site. Geotechnical drilling is used for in-depth site analysis, and is performed to establish whether a specific area is suitable for construction. This makes the process a mandatory part of any construction work in dense urban areas, where safety and urban architecture are of the utmost importance.

The process involves rock and soil sample collection, as well as drilling to determine soil stability for future foundations and construction. Moreover, the search for mineral deposits, oil, natural gases, and other valuable resources will also require careful geotechnical drilling.


Site analysis is crucial for large structures and other structure types in urban as well as rural areas. If proceeded without prior geotechnical drilling, hazardous soil conditions can prompt a structural collapse, or a devastating scenario during an earthquake or a flood. If you are planning to begin construction, be sure to take all the necessary precautions and adhere to the laws and regulations by hiring professionals to oversee the preparation process and ensure a successful construction project.


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