Nowadays, the construction industry is able to build huge infrastructures, such as concrete dams, motorways, cities in the middle of the desert, etc. However, at the planning and design stages, we do not really know yet how the ground will behave during construction. With the aim of reducing the geotechnical uncertainty, the industry carries out ground investigation campaigns to better know the ground properties. This ground information is sometimes necessary to properly make the designs of tunnels, deep foundations, tailing dams, etc.
At the end of the day, although we can make accurate soil behavior predictions by using sophisticated numerical tools, what will determine the real soil performance will be the ground measurements we can measure in the site. To do so, the industry found a way to obtain that data from the ground in real time: the geotechnical instrumentation.
There are several types of instruments used in construction, but the most common ones are the inclinometers, piezometers, extensometers and the conventional topography. Depending on the type of measurement that we want to obtain, we will use one instrument or another.
Nevertheless, the most important reason why the industry is using geotechnical instrumentation is basically because we can monitor the safety of the structure that we are building as well as other assets around the works that could be affected from the impact that construction causes.
As it happens, if we excavate a tunnel in soil, the natural behavior will be that the ground around the tunnel will change its stress conditions. This phenomenon hence will cause an impact to the tunnel itself but also to the buildings/structures on surface (i.e., causing ground settlements).
Previously to start the execution of works, if we install instruments into the ground and structures liable to be affected by the excavation works, we have the chance to follow-up how the ground conditions change over the time (vertical/horizontal displacements, water level, stress, or pressure, etc.).
In conclusion, monitoring an infrastructure is the safest and most reliable way to mitigate the risk in our projects.
To evaluate whether the measurements taken are acceptable or not, it’s necessary to previously define some threshold values. As the construction progresses, it’s convenient to keep checking if any of those levels are overcome in order to take a decision accordingly. In any case, the threshold values should be ideally defined in the project technical specifications.
Marc Llobet
Geotechnical Instrumentation Engineer
geotechnical, software engineer, geotechnical engineering software, construction AI, civil engineering software
