This　paper　investigates　the　performance　of　tunnel　boring　machines　(TBMs)　in　rock-soil　mixed-face　ground　based　on　TBM　tunneling　projects　in　Singapore.　Currently　several　methods　are　available　to　estimate　TBM　tunneling　performance　in　homogenous　rock　or　soil.　However,　the　existing　models　cannot　be　effectively　applied　to　predict　TBM　penetration　rate　in　mixed　ground.　The　tunnels　in　this　study　were　excavated　in　adverse　mixed-face　ground　conditions.　The　geological　profiles　and　the　TBM　operational　parameters　are　compiled　and　analyzed.　The　influence　of　different　geological　face　compositions　on　the　performance　of　the　TBMs　is　studied.　The　statistical　analysis　shows　that　there　is　a　possible　correlation　between　the　mixed-face　ground　characteristics　and　the　TBM　advancement.　Different　approaches　are　used　to　find　a　reliable　model.　Finally,　a　method　is　proposed　to　predict　the　TBM　performance　in　mixed-face　ground　for　project　planning　and　optimization.　(C)　2013　Elsevier　Ltd.　All　rights　reserved.