The　disc　cutter　is　one　of　the　most　TBM　cutting　tools　because　of　its　excellent　rock-breaking　capacity.　In　order　to　improve　the　efficiency　of　the　disc　cutter,　determining　the　appropriate　normal　force　is　an　effective　solution.　The　characteristics　of　rock　chips　formed　by　disc　cutter　are　important　indicators　to　comprehensively　reflect　the　rock　breaking　efficiency.　In　order　to　research　the　relationship　between　characteristic　particle　size　and　the　optimal　normal　force　of　the　disc　cutter,　the　linear　cutting　test　is　carried　out　and　the　effects　of　six　sets　of　TBM　disc　cutter　penetrations　on　the　particle　size　distribution　are　investigated.　The　data　of　rock　chips　from　test　and　the　characteristic　particle　size　theory　are　used　to　investigate　the　relationship　when　the　TBM　energy　consumption　is　consistent　with　Kich　similarity　theory,　Bond　hypothesis　and　Rittinger　new　surface　theory.　It　is　found　that　the　relationships　between　the　rock-breaking　consumption　energy,　characteristic　particle　size　and　penetration　are　both　in　accordance　with　the　quadratic　function.　Moreover,　the　formulas　between　the　optimal　normal　force　and　the　characteristic　particle　size　are　obtained,　which　provide　theoretical　basis　for　excavation　construction　in　the　similar　stratum.　©　2025　Ernst　&　Sohn　GmbH.