CAREER: The mechanics of subsurface urban heat islands

Overview: This CAREER proposal aims to investigate for the first time the mechanics of subsurface urban heat islands: increasingly observed regions of the ground beneath urban areas, which are warming up due to heat emitted by buildings, infrastructure, and underground transport. The rationale for this endeavor is that subsurface urban heat islands can detrimentally affect the integrity, appearance and durability of buildings and infrastructure due to the renowned deformation of soils and rocks caused by temperature variations. By leveraging an unprecedented sensing network that monitors the heat flows within and around underground tunnels, parking garages and basements in Chicago (one of the densest American cities, and thus most susceptible to underground warming), this project will develop and validate numerical investigations and machine learning prediction models. These investigations and models will unravel how heat flows associated with subsurface urban heat islands influence the deformation of soils and the buildings and infrastructures supported. This project will help further develop the multidisciplinary research program of the Principal Investigator (PI), which investigates the multiphysical and multiscale interactions between built environments and the shallow subsurface, with a focus on energy-related challenges. In the context of the NSF’s Big Idea “Harnessing the Data Revolution,” through the creation, analysis and interpretation of large datasets via sensing and computation, this project will remake the current scientific and educational boundaries on a fundamental subject that is at the dawn of pervasive effects for urban areas worldwide. Intellectual merit: Subsurface urban heat islands have never been addressed in the field of mechanics. Meanwhile, they have represented a critical subject in the fields of environmental science, hydrogeology and energy over the past ten years due to the environmental risks associated with ground warming and the promise to reuse substantial amounts of heat that would be wasted otherwise for meeting building energy needs. This CAREER research will shed light on the mechanics of subsurface urban heat islands, linking the microscopic mechanical response of soils subjected to temperature variations with the macroscopic response of buildings, districts and cities over time frames that vary from seconds to decades. Such an endeavor will have a threefold intellectual merit: (1) to unravel the significance of the deformation of soils underneath or around buildings and infrastructure caused by subsurface urban heat islands; (2) to investigate the stability and appearance of buildings and infrastructure due to the thermally induced deformation of soils; and (3) to predict the evolution and impacts of subsurface urban heat islands for site-specific features. Experimental, theoretical and computational knowledge will be developed via a world-first subsurface sensing network, advanced numerical simulations and machine learning prediction models, respectively. The PI is uniquely poised to address this investigation due to his multidisciplinary training in geomechanics, structural mechanics and energy, and competence in experimental and theoretical analysis approaches. Broader impacts: This innovative project has the potential to shape a new area of study on subsurface urban heat islands, which can serve transformative strategies to plan, design and manage the underground of cities. The achievement of a fundamental understanding of the mechanics of subsurface heat islands can specifically ant