Abstract:

Evaluating the damage risk level of water and mud inrush during the construction under water-rich, high-pressure, and unfavorable geological conditions is a challenge for the construction design of underground tunnels. Analyzing the interactions between excavation stress and seepage is crucial for accurately simulating the evolution of water and mud inrush during tunnel construction. We propose a method to calculate the damage coefficient of surrounding rock corresponding to the damage characteristics in different deformation stages based on its damage evolution during excavation load release, and further examines how this damage affects the rock’s permeability coefficient. Furthermore, we introduce a calculation method for determining the critical water inrush coefficient of surrounding rock based on its failure characteristics and water inrush mechanisms. According to the damage and permeability of surrounding rock, we categorize the water and mud inrush damage into four risk levels, providing the basis for assessing the risk of such damage in underground tunnel construction. Finally, we present a coupling calculation method that integrates variable damage stiffness, weighted grading of excavation load, and iterative application of seepage load. This method simulates the evolution of water and mud inrush during tunnel excavation. Application of this method in engineering practice demonstrates its effectiveness, offering a viable approach for assessing water and mud inrush risks in underground tunnel projects.

Key words: water and mud inrush, underground tunnels, construction excavation, numerical simulation, coupled iteration