New study finds signs of underground climate change and influence on civil infrastructure

A new study by Alessandro F. Rotta Loria of Northwestern University, titled “The silent impact of underground climate change on civil infrastructure”, that was recently published in the Communications Engineering journal showed proof of underground “climate change” and its results on civil infrastructure.

Furthermore, more than 150 temperature sensors were installed across the underground space of the Chicago Loop area, the second most densely populated area in the US after Manhattan.

An additional 3D finite element model was created, capable of simulating the thermo-hydro-mechanical behavior of the area. The simulations considered different timeframes, with the 100-year period between 1951 and 2051 being the broader one, and were compared to the in-situ measurements.

One of the main notes in the study was how underground structures, such as basements, underground parking garages, subway tunnels, high voltage cables etc. contribute to gradual heating of the subsurface, leading to subsurface urban heat islands.

In the case of the Chicago Loop studied, the subsurface mainly consists of clay materials which exhibit a dilative behavior due to thermal expansion.

The study concluded that this expansion could lead to long term ground displacements that vary compared to the ones that the structures had been designed for, especially older ones.

These displacements are not found to be great enough to cause structural failures, but can lead to problems related to durability, esthetic, and operational requirements.

Finally, the study identified two main mitigation measures. The first one was the reduction of heat losses, by implementing heat insulation, according to modern standards, in older buildings and infrastructure, while the second one was harnessing any large waste heat from subsurface.