It　is　widely　recognized　that　the　improvement　effects　of　the　foam　on　the　soil　properties　during　earth　pressure　balance　shield　(EPBS)　tunnelling　can　be　well　characterized　by　some　conditioning　evaluation　indices　such　as　shear　strength,　flowability,　and　compressibility.　The　number　of　EPBS　has　increased　significantly　worldwide　in　the　past　few　decades.　Consequently,　recycling　the　EPBS　muck　wastes　for　other　applications　becomes　important,　and　in　this　context,　estimating　the　recycling　potential　of　foam-conditioned　soils　is　of　great　practical　significance.　Although　numerous　studies　have　proved　dewaterability　to　be　one　of　the　most　important　indices　to　assess　the　reusability　of　clay　muck　wastes,　the　dewatering　behaviors　of　foam-conditioned　clay　soils　and　their　quantitative　interrelations　with　common　conditioning　evaluation　indices　are　still　not　properly　understood.　To　understand　the　comprehensive　effects　of　foams　on　high-saturation　clay　soil　that　is　comparable　to　natural　clays　of　real　tunnels,　a　series　of　laboratory　experiments　were　carried　out,　including　undrained　shear　tests,　flowability　tests,　and　vacuum　filtration　tests.　The　concept　of　specific　resistance　was　introduced　to　characterize　the　dewaterability,　taking　the　effects　of　filtration　time　and　pressure　into　consideration.　The　moisture　migration　mechanisms　at　both　the　conditioning　and　dewatering　stages　were　analyzed　using　low-field　nuclear　magnetic　resonance　tests.　It　was　found　that　increasing　the　degree　of　saturation　and　the　foam　injection　ratio　could　lead　to　a　significant　enhancement　in　the　flowability　(vertical　and　horizontal　slumps),　compressibility,　and　dewaterability,　but　a　reduction　in　the　undrained　shear　strength.　The　injected　foams　caused　the　moisture　to　migrate　from　micropores　to　mesopores　during　conditioning,　but　from　mesopores　to　micropores　and　macropores　during　dewatering.　Accordingly,　quantitative　expressions　were　established　to　determine　the　interrelations　between　conditioning　and　dewatering　indices.　The　specific　resistance　was　also　demonstrated　to　be　an　effective　alternative　variable　to　characterize　the　conditioning　performance　of　foams　for　high-saturation　clay　soils.　Finally,　a　new　application　diagram　of　different　evaluation　indices,　which　can　assist　engineers　in　effectively　assessing　the　foam＇s　effects　on　clay　soils,　was　provided　to　contribute　valuable　knowledge　to　EPBS　tunnelling　practices.　©　2024　Elsevier　Ltd