Land　reclamation　from　the　sea　is　increasingly　common　in　coastal　areas　in　China　as　its　urban　population　continues　to　grow　and　the　construction　of　subways　in　these　areas　becomes　an　effective　way　to　alleviate　transportation　problems.　Earth　pressure　balance　shield　(EPBS)　tunneling　in　reclaimed　lands　often　faces　the　problem　of　seawater　erosion　which　can　significantly　affect　the　effectiveness　of　soil　conditioning.　To　investigate　the　impacts,　in　this　work,　the　stratum　adaptability　of　EPBS　foaming　agents　in　seawater　environments　was　evaluated　based　on　a　series　of　laboratory　tests.　The　Atterberg　limits　and　vane　shear　tests　were　carried　out　to　understand　the　evolution　characteristics　of　mechanical　properties　of　clay-rich　soils　soaked　in　seawater　and　then　conditioned　with　foams.　The　results　revealed　that,　for　the　same　foaming　agents,　the　liquid　limit　and　plastic　limit　of　soils　soaked　in　seawater　were　lower　than　those　in　deionized　water　due　to　the　thinning　of　bound　water　films　adsorbed　on　the　surface　of　soil　particles.　Similarly,　soils　soaked　in　seawater　had　lower　shear　strength.　In　addition,　the　results　indicated　that　the　foam　volume　(FV)　produced　by　foaming　agents　using　seawater　as　the　solvent　was　slightly　higher　than　that　when　using　the　deionized　water　due　to　the　higher　hydration　capacity　of　inorganic　salt　cations　in　seawater　compared　with　organic　substances.　It　was　also　shown　that　seawater　had　negative　effects　on　the　half-life　time　(T1/2)　and　the　dynamic　viscosity　(η)　of　foaming　agents　due　to　the　neutralization　reaction　between　anions　in　the　foaming　agents　and　Na+　present　in　seawater.　The　test　results　also　confirmed　that　0.5　%　of　the　tackifier　(CMC)　can　alleviate　the　issue　of　thin　foam　films　caused　by　seawater　intrusion　and　improve　the　dynamic　viscosity　of　foaming　agents　more　effectively,　leading　to　superior　resistance　to　seawater　intrusion　in　EPBS　tunnel　constructions.　©　2025