The　water-rich　mountain　tunnels,　passing　through　the　fault　zone,　often　encounter　the　water　inrush　and　discharge　during　construction,　resulting　in　construction　stagnation　and　groundwater　loss.　To　investigate　the　influence　of　grouting　on　water　discharge　in　fault　zones,　the　simplified　tunnel　discharge　model　in　fault　zone　was　established　based　on　the　composite　lining　mountain　tunnels.　The　equivalent　fault　method　was　used　in　space,　and　the　fault　was　used　as　the　supply　boundary　with　the　image　method.　The　formula　for　deep-buried　tunnel　discharge　considering　the　grouting　circle　effect　was　derived.　The　relations　between　tunnel　discharge　and　parameters　(e.　g.,　grouting　circle　thickness,　and　relative　permeability　of　grouting　circle)　were　obtained.　The　proposed　method　applicability　and　correctness　and　the　semi-analytical　solution　were　verified　through　the　degenerate　solutions　and　numerical　models.　The　parameter　analysis　was　performed　on　the　groundwater　level,　lining　thickness,　and　grouting　circle　of　tunnel　discharge.　The　result　indicates　that　the　main　controlling　factors　for　water-rich　mountain　tunnel　discharge　in　the　fault　zone　are　the　grouting　circle　thickness,　the　relative　permeability　coefficient　of　grouting　circle,　and　the　lining　thickness.　Under　the　condition　of　constant　groundwater　level,　the　tunnel　discharge　is　significantly　affected　by　the　distance　between　fault　and　tunnel.　The　thicker　the　lining,　the　stronger　the　water　blocking　effect,　and　the　smaller　the　tunnel　discharge　in　the　fault　zone.　The　relative　permeability　coefficient　of　grouting　circle　is　sensitive　to　the　tunnel　discharge　effect.　When　the　ratio　of　surrounding　rock　permeability　coefficient　to　grouting　circle　permeability　coefficient　is　less　than　50,　there　is　a　linear　relation　between　discharge　and　grouting　circle　thickness.　However,　when　the　grouting　circle　permeability　coefficient　is　less,　the　grouting　circle　thickness　has　a　significant　effect　on　tunnel　discharge.　For　the　mountain　tunnel　waterproof　and　drainage　design,　in　the　case　of　ensuring　grouting　circle　thickness,　the　priority　should　be　given　to　optimizing　the　grouting　material　permeability　to　achieve　more　efficient　groundwater　control.　In　the　case　of　ensuring　grouting　ring　thickness,　the　priority　should　be　given　to　optimizing　the　permeability　of　grouting　material.　The　study　result　aims　to　provide　the　reference　and　guidance　for　the　design　and　construction　practice　to　facilitate　the　water　blocking　and　grouting　study　for　tunnels　crossing　fault.　©　2024　Editorial　Department　of　Journal　of　Highway　and　Transportation　Research　and　Development.　All　rights　reserved.