Stability of Solution Cavities in Urban Developments: A Case Study Towards Enhancing Geohazard Risk Assessment

Abstract

Karst cavities in fissured soluble rock represent serious geotechnical hazard for civil construction and urban development. The process of cavity formation, expansion, and propagation is difficult to predict because it is driven by a combination of diverse causes, such as the dissolution rate of rock; flow of groundwater; amount of fine material within rock layers; presence of loose, uncontrolled fill over the rock; and the leakage of underground utilities. Several factors can affect cavity stability, including cavity geometry and dimensions, cavity depth, overburden surface-layer lithology, and surface-loading conditions. This paper presents a case study for karst cavities stability in the Abu Dhabi Municipality (ADM) of the United Arab Emirates as part of a comprehensive study initiated by the ADM to address the geotechnical, geologic, and hydrogeological hazards encountered in the municipality. The purpose of this study is to develop a methodology for assessing karst cavities stability in the ADM, and thereby, quantify their potential hazard for civil construction and urban development in the municipality. A numerical study is performed, using a finite difference model that is based on site-specific ground conditions encountered in a localized area. Results from this numerical investigation are presented in the form of stability charts for different lithologic and surfaceloading conditions. These charts are used to develop a set of geographic information system cavity-collapse geohazard maps for the study area to factor solution cavity-collapse risk into an integrated geohazard map for the ADM. Based on available information and the case study presented herein, it is concluded that the collapse of solution cavities do not significantly contribute to the geotechnical hazard observed in the ADM.

Upper bound limit analysis of roof collapse of deep cavities in unsaturated soils

“…Underground cavities are easily formed by natural processes or engineering constructions. [1][2][3][4][5][6] Owing to changes in the boundary conditions and the redistribution of stress near the underground cavity, the roof may collapse. The collapse zone above the cavity roof is often confined to a specific region rather than extending to the ground surface when the cavity roof lies deep below the ground surface.…”

“…Underground cavities are easily formed by natural processes or engineering constructions 1–6 . Owing to changes in the boundary conditions and the redistribution of stress near the underground cavity, the roof may collapse.…”