Model test for water inrush caused by karst caves filled with confined water in tunnels

Abstract

In this study, a water inrush model test system for high ground stresses and hypertonic tunnels is developed to examine the evolution process of karst cave water inrush events induced by tunnel construction and rainfall. A 3D fluid-solid coupling model test is performed to simulate the tunnel excavation and increasing karst cave water pressure, and the evolutionary mechanism of karst water inrush induced by tunnel construction is revealed. The results indicate that seepage occurs during the tunnel excavation, and water seepage ceases after timely support. During hydraulic loading, the experiment successively obtained the stages corresponding to the occurrence of partial dripping, water streams, support bulging, partial and complete support block falls, and water inrush. The influence of tunnel excavation on the stability of the surrounding rock of the monitoring surface increases sharply when the distance between the tunnel excavation surface and the monitoring surface is approximately 0.5–1 times the diameter of the tunnel. The research results are significant for studies examining the water inrush mechanism and the prevention of tunnel water inrush disasters.