A FAHP-EWM Combined Weights-Based Two-Dimensional Cloud Model for Risk Assessment of Water Inrush Hazards in Tunnels Through Water-Rich Karst Strata

The accurate assessment of water inrush risks is crucial for tunnel safety in water-rich karst areas. This study introduces a risk assessment method based on a two-dimensional cloud model to address the associated uncertainties. A comprehensive risk indicator system is established, covering five principal factors: stratigraphic lithology, geological structure, topography, natural geography, and construction activities. The weights of these indicators are determined using an integrated Fuzzy Analytic Hierarchy Process and Entropy Weight Method. A two-dimensional cloud model is constructed, incorporating the dual dimensions of risk probability and loss severity. The risk level is then determined by analyzing the distribution of synthesized cloud droplets across predefined risk zones. Applied to the Andangnong Tunnel project, this methodology evaluates the water inrush risk as greater risk (Level II), a result consistent with the project’s dedicated safety assessment. Following the targeted treatment of key karst caves (Y5-2 and Y2-2), the risk level was successfully reduced to low risk (Level IV). This approach provides a scientific basis for risk management in similar geotechnical engineering contexts.