Land Subsidence in Arid Terrain: Methodology toward Risk Analysis

Abstract

Addressing land subsidence requires the identification of root causes, modeling its initiation failure modes, and managing this risk in a cost-effective manner. This paper presents a methodology for quantifying and managing the risk of land subsidence resulting from underground cavities and illustrates this methodology using a case study of a site that was exposed to such a phenomenon in Kuwait. The methodology produces the hazard and risk profiles by computing the probability of sinkhole formation over a selected geographic area based on field data and examining spatial characteristics of the cavities. Developing the methodology required reviewing project plans and relevant reports, defining decision processes relating to land subsidence resulting from underground cavities, examining the spatial characteristics of cavities, performing reliability analysis for a selected failure mode, and performing regression analysis for predicting grout volume needed to fill in cavities. Considering for illustration purposes one of the failure modes without the important effects of the water table resulted in a very small failure probability. Future studies should take into consideration the development of performance functions and limit states for other failure modes, including the effects of the water table. The spatial analysis of cavities confirmed their random layout without any spatial trends or characteristics. A regression model for predicting grout volume as a function of cavity height was developed with statistically significant regression coefficients, a small correlation coefficient, and a low reliability level for prediction.