Treatment for Salvaging Inundated Tunnels Due to Mine Water Inrush Using Aggregates Pouring and Grouting: A Review

Chinese coal mines have been seriously threatened and restricted by water disasters for a long time. The prevention and control of the inundation by groundwater inrush in large cross-section tunnels face several difficulties, such as issues dealing with high-water pressure, large flow rate, and plugging. The approach of grouting after aggregate pouring has been widely adopted in practice. This paper reviews the state-of-the-art on aggregate pouring and grouting treatment mechanism of the inundated tunnel by mine water inrush. Methods including geological investigation, scale model test, numerical simulation, and theoretical analysis were used to carry out the study. The scale model test can be classified into different types according to the test conditions such as pipeline material, the shape of the pipeline cross-section, the number of the aggregate pouring borehole, and pipe inner wall roughness. The settlement and migration characteristics of aggregates in inundated tunnels were discussed according to the model tests, numerical simulations, and theoretical analysis results. The criteria for the plugging effect of aggregate accumulation in inundated tunnels were analysed. A model test platform that needs to be further studied and developed to meet the actual engineering geological conditions was put forward. The research on grouting in the aggregate accumulation mass as well as the grout propagation and solidification in saturated aggregates can further provide a scientific basis for improving the design of grouting blocking projects in large section inundated tunnels.