To build in urban environments, we must be able to see under the ground and be able of handling large quantities of geotechnical and geological information. Not just clay strata and rock with crack zones. Nowadays, homes, roads and railways are also being built on industrial plots with contaminated land as well as areas where abandoned rubbish tips lie hidden.

Tyréns is running an active development process on geological modelling as part of the national R&D programme TRUST (TRansparent Underground STructure). The TRUST project is about making the underground structures more transparent. Both to build more efficiently underground and to build safely on the surface. Tyréns is participating in two of the sub-projects:

  • TRUST 2.1 Geo-electrical surveys for the investigation of underground infrastructure in urban environments
  • TRUST 4.1 Geo-BIM - Method for the rational assessment of geotechnical data for underground infrastructure in urban environments

In sub-project 2.1, Tyréns is developing an investigative method based on geo-electrical surveys. This method can provide a spatial image of the way things appear underground in an area or along a corridor. The underground can now be visualised in 3D.

“The method is best used for investigating the engineering and structural engineering aspects at an early stage. It provides a comprehensive image of what exists under the ground, as a complement to point by point sampling,” Mats Svensson, Project Manager for TRUST at Tyréns, says.

Complex urban environments
During autumn 2014, field tests were undertaken, including in the Färgaren quarter in Kristianstad. In 2015, the tool was used for measurements and tests in the Stockholm Bypass project and at Äspö HRL.
“The Stockholm Bypass passes through all sorts of land but, in just the same way as in all urban densification, areas that have been left over or have had other functions, such as old industrial plots, are being used,” Mats Svensson says.

The method is being developed, as part of the TRUST project, specifically for the complexity to be found in urban environments, where, among other things, it is necessary to filter out interference from electromagnetic fields emanating from railways and power lines.

“The urban environment is crowded, which entails challenges both in terms of measurement and interpretation. It isn’t the same as laying out a measurement line on a field,” Mats Svensson says.
The method can show all types of structures underground, such as the thickness and strength of clays and moraine strata, presence of water, the distance to bedrock and the extent of crack zones. Nevertheless, Tyréns’ most important contribution to the project is characterising contaminants, for example, from old dry cleaners as well as the extent and content of old landfills.

Inspection of landfills
In an earlier project, MaLaGa, Tyréns’ geotechnical engineers demonstrated that it is possible to distinguish between different types of waste with the help of geotechnical methods. This is based on the fact that different materials – not just metals but even salts and suchlike – have different conductivities.
“In the Malaga project, we developed a method for detecting methane gas and gas movements in landfills. We also demonstrated how the extent of the actual landfill could be measured. In the TRUST project, we have taken the method further. Put simply, we can now see deeper and wider, while we are refining the method so we can see in more detail what lies under the surface,” Mats Svensson says.
In parallel with the project, one of Tyréns’ postgraduates, Sara Johansson, is investigating how to study in detail which materials are hidden in a landfill.
“This involves lab tests on very pure type materials. Eventually, this may open up the possibility of landfill mining; that is to say, extracting metals and other materials from old rubbish tips,” Mats Svensson says.

See the website for TRUST. Also, watch the demonstration films on geological modelling:
"Geological modelling Part 1"
"Geological modelling Part 2"

Client: Financiers: Formas, Sven Tyréns Stiftelse and BeFo