Caverns　are　generally　formed　by　a　combination　of　regional　geological　action　and　groundwater,　and　their　improper　treatment　will　inevitably　lead　to　dangerous　conditions　in　underground　works.　To　detect　the　specific　failure　mechanism　of　tunnel-surrounding　rock　induced　by　invisible　caverns,　a　true　triaxial　compression　test　is　conducted,　accompanied　by　acoustic　emission　technology　and　an　internal　borehole　camera,　for　monitoring　the　acoustic　response　and　visible　secondary　cracks,　and　a　corresponding　DEM　simulation　is　carried　out　to　reveal　the　meso-mechanism.　The　results　indicate　the　following:　(1)　The　invisible　cavern　demonstrates　a　negative　influence　on　the　stability　of　the　tunnel　and　leads　to　a　25.82%　reduction　in　the　peak　z-axis　load　of　the　specimens.　(2)　The　acoustic　emission　results　show　that　the　relatively　severe　dominant　failures　mainly　occur　near　the　peak　stress　in　all　types　of　specimens,　and　the　speed　and　intensity　of　the　cavern-existing　specimen　is　significantly　greater　than　that　of　the　cavern-free　specimen.　(3)　The　cavity-free　tunnel　shows　mirror-symmetric　splitting　failure　on　the　left　and　right　sidewalls,　while　the　secondary　cracks　appear　earlier　and　show　asymmetrical　distribution　in　the　cavern-existing　specimen,　and　the　volume　of　broken　rock　blocks　near　the　free　surface　is　larger.　(4)　The　cavern　directly　changes　the　failure　process　of　the　tunnel-surrounding　rock　(intermediate　rock　failure　occurs　earlier　than　splitting　failure),　the　distribution　of　principal　stress,　and　the　corresponding　mechanism　of　secondary　failures.　(5)　Application　of　the　displacement　and　velocity　trend　fields　helped　to　reveal　accurate　failure　procedures　in　the　true　triaxial　test.