Stability Analysis of Karst Tunnels Based on a Strain Hardening–Softening Model and Seepage Characteristics

There are more and tunnel projects in the karst-developed areas Southwest China. Affected by karst caves water, tunnels often experience geological disasters such as local collapses water inrush. A simplified rock stress hardening-softening model was established based on triaxial compression test results of two kinds carbonatite to accurately analyze deformation inrush characteristics surrounding rocks after excavation. The total stress–strain curve into four linear stages: elastic stage, strain hardening strain-softening residual stage. volumetric strain–axial corresponding expansion slow rapid stable hardening–softening used deduce relationship between rocks’ mechanical parameters cohesion, internal friction angle, dilatancy plastic strain, well seepage characteristic permeability coefficient, porosity, strain. Chongqing, China taken engineering background. constitutive were applied FLAC3D numerical simulation programming language FISH stability overlying confining caves. showed that masses cave prone overall sliding instability. Confined intruded through shear-slip rupture zone both sides instead shortest path. Two points existed surface. variation law coefficients could truly reflect whether there a channel cave, permeable area speed channel. work provides new idea for control tunnels.