Ground Deformations in Chicago Buildings Linked to Underground Climate Change, New Study Reveals
An exploratory study conducted by Northwestern University has discovered a link between ground deformations in Chicago buildings and underground climate change. Using a wireless network of temperature sensors above and below ground across the Loop, Alessandro Rotta Loria, an assistant professor of civil and environmental engineering, found that the diffusion of heat from buildings, garages, basements, and transportation systems into the ground is causing the ground to contract and expand, resulting in sinking and cracking of buildings.
Although the sinking is happening slowly and doesn’t pose an immediate danger to residents, it could lead to costly maintenance and retrofitting bills for building owners. Moreover, cracks in walls can be concerning for residents. Rotta Loria refers to this phenomenon as a silent hazard as it is not immediately visible but can have long-term implications for building infrastructures.
The study, published last month in the journal Communications Engineering, is said to be the first of its kind. Rotta Loria emphasizes that more research needs to be done to understand which civil structures and infrastructures are particularly vulnerable to underground climate change.
Local building developers and insurance professionals have noted that they are not currently planning any changes to their buildings until further research is conducted. However, they do acknowledge the potential impact of underground climate change on sustainability efforts, especially as energy costs continue to rise.
While the underground temperatures in downtown Chicago may not be as high as in cities with larger underground transportation systems, such as London and New York City, the Millennium Parking Garage complex presented an ideal location for research due to its size and density.
As part of the study, Rotta Loria built a 3-D computer model to simulate ground temperature changes since 1951, the year Chicago completed its subway tunnels. The simulations showed that higher temperatures can cause soil like limestone and clay to either swell and expand upward or contract and sink downward.
By comparing data collected from sensors near underground infrastructure with data from sensors buried in green spaces like Grant Park, the researchers found that underground temperatures beneath the Loop are often 18 degrees Fahrenheit higher than temperatures below Grant Park.
Chris Semlies, an assistant vice president at Zurich North America, considers regular inspections to be crucial for checking deterioration and cracks in underground structures, although he currently does not see an enhanced risk for parking garages or other similar structures.
Overall, the study sheds light on the previously unrecognized issue of underground climate change and its impact on building infrastructures. As research continues, it is expected to provide valuable insights for urban areas worldwide to mitigate potential operational issues caused by this phenomenon.
