Fault　fracture　zones　are　adverse　geological　conditions　often　encountered　in　the　constructions　of　mountain　tunnels.　Extensive　structural　damage　to　the　mountain　tunnels　in　adjacent　to　the　fault　fracture　zones　has　been　documented　in　the　past　earthquakes.　In　current　work,　three-dimensional　numerical　model　of　a　water　conveyance　tunnel　crossing　multiple　active　strike-slip　faults　was　established　to　assess　the　structural　damage　with　consideration　of　four　primary　influence　factors:　the　magnitude　of　fault　movement,　the　distance　between　adjacent　fault　planes,　the　tunnel-fault　intersection　angle　and　the　mechanical　properties　of　the　rock　mass　in　the　fault　fracture　zone.　Two　quantitative　damage　indices,　namely,　the　overall　structural　damage　index　and　the　concrete　lining　crack　width,　are　proposed　in　this　study　to　investigate　the　structural　integraty　and　the　serviceability　of　the　water　conveyance　tunnel　subjected　to　fault　movements.　The　numerical　results　indicate　that　the　cross-sectional　damage　of　the　tunnels　primarily　concentrated　in　the　vicinities　of　the　fault　planes,　and　the　boundaries　between　the　fault　and　the　competent　rock.　With　the　increase　of　the　distance　between　adjacent　fault　planes,　the　structural　damage　of　the　tunnel　in　the　region　near　the　center　of　the　fault　fracture　zone　rapidly　decreases.　The　tunnel-fault　intersection　angle　also　significantly　affects　the　performance　of　the　tunnel　under　fault　movement.　Moreover,　the　increase　of　surrounding　rock　mass　stiffness　in　the　fault　fracture　zone　reduces　the　extension　but　increases　the　severity　of　damage　to　the　tunnel　lining.　Overall,　the　numerical　results　of　this　study　provide　a　better　understanding　of　the　response　of　mountain　tunnels　under　multiple　strike-slip　fault　movement.