Seismic　fragility　analysis　can　quantitatively　evaluate　the　seismic　performance　of　structures　from　a　probabilistic　viewpoint　and　accurately　characterize　the　relationship　between　the　degree　of　structural　damage　and　ground　motion　intensity.　This　study　investigates　the　seismic　fragility　of　shield　tunnels　in　three　different　liquefiable　and　non-liquefiable　soils.　A　plane-strain　finite　element　model　of　the　saturated　soil　and　shield　tunnel　is　established　via　the　OpenSees　computational　platform　employing　the　multi-yield　surface　elastoplastic　PressureDependMultiYield　and　PressureIndependMultiYield　models　to　simulate　the　constitutive　behaviour　of　liquefiable　and　non-liquefiable　soils.　The　developed　model　is　utilized　to　conduct　nonlinear　dynamic　effective　stress　time　history　analyses　to　generate　the　seismic　fragility　curves　and　surfaces　based　on　the　incremental　dynamic　analysis　method.　Meanwhile,　appropriate　scalar-　and　vector-valued　intensity　measures　are　identified　based　on　their　correlation,　efficiency,　practicality　and　proficiency.　Compared　with　the　fragility　curves　based　on　scalar-valued　intensity　measures,　the　fragility　surfaces　based　on　the　vector-valued　intensity　measures　can　better　describe　the　effect　of　ground　motion　characteristics　on　the　structural　seismic　demand,　and　thus　can　more　accurately　assess　the　structural　seismic　performance.　The　seismic　damage　probabilities　derived　from　the　fragility　curves　and　surfaces　reveal　that　the　seismic　damage　risk　of　the　shield　tunnel　in　sandwiched　liquefiable　soil　deposit　is　higher　than　that　of　the　tunnel　structure　located　in　entirely　liquefiable　or　non-liquefiable　soil　profiles.　This　finding　underscores　the　importance　of　carefully　evaluating　the　seismic　safety　of　shield　tunnels　situated　in　sandwiched　liquefiable　soil　deposits.　©　2024　Elsevier　Ltd