Method and Validation for Tunnel Face Collapse Risk Analysis Considering Construction Sequence
Rock tunnel excavation using the drill-and-blast method often involves multiple concurrent operations and encounters complex geological conditions,leading to the occurrence of tunnel face col-lapse accidents.To analyze the risk of tunnel face collapse during tunnel construction,a risk analysis method considering the temporality sequence of basic events during rock tunnel construction was pro-posed,utilizing T-S(Takagi-Sugeno)fuzzy fault trees and Bayesian network.Extensive research was conducted on 46 tunnel face collapse accidents in rock tunnels excavated using the drill-and-blast meth-od.Thirty hazardous factors and risk-prone environments were identified as basic events.The occur-rence probabilities and conditional probabilities between nodes were quantitatively calculated based on statistical data,generating fuzzy subsets for the occurrence probabilities of each basic event.A T-S fuzzy fault tree for tunnel face collapse was constructed and mapped to a Bayesian network.By em-ploying the bidirectional inference capability of Bayesian networks,the posterior probabilities and im-portance of each basic event were calculated,and the key basic events that had a significant impact on tunnel face collapse were identified and selected.Furthermore,considering the temporal occurrence of basic events during the tunnel construction process,the risk status of corresponding events was se-quentially updated in the Bayesian network,enabling the assessment of the temporal variations in the probability of tunnel face collapse risk.Using the collapse accident in the Youfangping Tunnel as an engineering example,the feasibility and challenges of considering construction sequencing in the risk analysis of tunnel collapses during tunnel construction were discussed,Risk management strategies and focal points for different construction phases of rock tunnels were provided.This research offers a novel theoretical framework and technical means for the analysis and management of safety risks in rock tunnel construction.
rock tunneltunnel face collapseT-S fault treebayesian networkrisk analysistime se-quence