Quantification of Margins and Uncertainties for the Risk of Water Inrush in a Karst Tunnel: Representations of Epistemic Uncertainty with Probability

Abstract

Accidents involving water inrush in karst tunnels often occur in China, resulting in serious social impact and huge economic loss. So, it is important that engineers provide a method with which to evaluate the risk of water inrush in karst tunnels. There are some problems regarding water inrush such as nonlinearity, and nominal, uncertain variables. Based on the mathematical model of water inrush, this paper proposes a methodology including a mechanical model dependent on geology and a mathematical model with quantification of margins and uncertainties (QMU), to evaluate the risk of water inrush. The following subjects are considered: (1) the risk assessment model is combined with mechanical analysis of water inrush in the karst tunnel in a perfect, dynamic way, (2) the analysis of uncertainty in QMU in the risk of water inrush, (3) the representations of uncertainty with probability theory, (4) the QMU analyses containing only epistemic uncertainty are represented, (5) the sensitivity analysis of parameters was performed through a step-wise regression analysis. This synthetic risk evaluation system provides a powerful and novel tool for systematically evaluating water inrush risk in karst tunnels.