Analysis of tunnel water inrush accidents induced by stratum collapse models

As tunnel engineering progresses, the complexity of geological strata and the presence of water bodies beneath tunnels have exacerbated the risk of water inrush incidents. Mutation theory is utilized to elucidate the mechanisms underlying stratum collapse-induced water inrush, with the Shijingshan Tunnel's water inrush pattern identified as stratum collapse-induced. Finite element method (FEM) numerical models were developed for four conditions: original tunnel, Grade III surrounding rock, advanced grouting reinforcement, and sectional excavation. The evolution of the plastic zone, deformation, and support forces in the surrounding rock was compared across these models. The study demonstrates that shear failure of the rock mass, induced by concentrated stress and water pressure during excavation, results in the formation of water inrush pathways. Advanced grouting and sectional excavation effectively reduced the plastic zone and vertical deformation. This mitigation lessened support damage and decreased the likelihood of stratum collapse. This paper offers technical support and case analysis for the prevention of stratum collapse-induced water inrush in underwater blasting operations. • A prediction model of water inrush for stratum subsidence is proposed. • The formation mechanism of stratum collapse water inrush mode was systematically elucidated. • A fluid-solid coupling model is established to investigate the response of tunnel structures. • The causes and laws of accidents are summarized via case analysis.