Determining building risks associated with land subsidence in the Netherlands

A new modeling technique discussed in the International Journal of Masonry Research and Innovation shows how building risks associated with land subsidence in The Netherlands can be determined.

Land subsidence, when the ground sinks due to either natural or human-induced factors, or both, is becoming an increasingly serious issue in many parts of the world, particularly in low-lying regions like The Netherlands. According to Alfonso Prosperi, Michele Longo, Paul A. Korswagen, Mandy Korff, and Jan G. Rots of Delft University of Technology in Stevinweg, The Netherlands, this phenomenon, exacerbated by climate change, threatens buildings, infrastructure, and the very fabric of urban environments.

For building on shallow systems, such as strip foundations, subsidence can cause minor but recurring cracks, compromising both the functionality and aesthetics of a building. The new work looks at how advanced numerical modeling strategies can predict the impact of subsidence on buildings, with a focus on the particularly vulnerable two-story masonry buildings that make up a significant portion of the Dutch housing stock. This research has important implications for urban planning, risk assessment, and the long-term resilience of cities in the face of ongoing climate changes.

The team compared two approaches for modeling subsidence: the coupled and the uncoupled methods. Both strategies use nonlinear finite element (FE) analysis, a computer simulation, to predict how structures might respond to physical forces. The challenge in such simulations lies in accurately representing the relationship between the soil and the building, the soil-structure interaction. Understanding this is critical for predicting how ground movements will affect a building.

In the coupled model, the building and surrounding soil are treated as a single system. This method integrates the building with the ground, using contact interfaces to allow the structure to interact with the soil. In the uncoupled model, the building and soil are kept separate; they are treated as independent systems.

The team tested both models under identical conditions. Initially, their results were similar when the simulated soil volume was small. However, as the volume of soil increased, the models began to diverge. The coupled model showed that including a larger volume of soil could reduce predicted damage by up to 50%, highlighting how the broader soil environment significantly influences the structural response.

One particularly important insight from the study is the role of angular distortion, the degree to which a structure bends, as a reliable indicator of putative damage. This finding could help engineers and urban planners better assess risks and determine which buildings are at greatest risk of subsidence-related damage.