District-scale numerical analysis of settlements related to ground water lowering in variable soil conditions

Abstract

This study presents a novel framework in which numerical modelling contributes to the performance of district-scale subsidence-induced damage assessment in cities where ground settlements affect entire quarters. Therein, the implementation of expeditious procedures offers geotechnical engineers the possibility of contributing beyond the typical site scale. For this purpose, several “typified” hydro-geomechanical-loading (HGL) models, which represent (simplified) scenarios of masonry buildings undergoing settlements, were set up to account for different predisposing/triggering factors (i.e. soil heterogeneity, loading conditions, and groundwater variations) of settlement occurrence in built-up areas. These models exploit multi-source wide-area input datasets encompassing the hydro-mechanical properties of geomaterials, in situ investigations and measurements (e.g. groundwater levels in wells), and innovative remote sensing data (i.e. DInSAR techniques). With reference to a district in Rotterdam City (the Netherlands), which was built on “soft soils”, the numerical simulations of different scenarios i) provide an overview of the comparative role of predisposing/triggering factors on settlement occurrence and ii) allow assessments of the expected induced damage to masonry buildings over thirty years with the exploitation of fragility curves. Considering the widespread diffusion of such geohazards, the proposed approach could help prioritise (rather expensive) maintenance work to the built heritage within sustainable strategies for subsidence risk mitigation.