In　this　study,　various　countermeasures　used　to　mitigate　tunnel　deformations　due　to　nearby　multi-propped　basement　excavation　in　soft　clay　are　explored　by　three-dimensional　numerical　analyses.　Field　measurements　are　used　to　calibrate　the　numerical　model　and　model　parameters.　Since　concrete　slabs　can　constrain　soil　and　retaining　wall　movements,　tunnel　movements　reach　the　maximum　value　when　soils　are　excavated　to　the　formation　level　of　basement.　Deformation　shapes　of　an　existing　tunnel　due　to　adjacent　basement　excavation　are　greatly　affected　by　relative　position　between　tunnel　and　basement.　When　the　tunnel　is　located　above　or　far　below　the　formation　level　of　basement,　it　elongates　downward-toward　or　upward-toward　the　basement,　respectively.　It　is　found　that　tunnel　movements　concentrate　in　a　triangular　zone　with　a　width　of　2　He　(i.e.,　final　excavation　depth)　and　a　depth　of　1　D　(i.e.,　tunnel　diameter)　above　or　1　D　below　the　formation　level　of　basement.　By　increasing　retaining　wall　thickness　from　0.4　m　to　0.9　m,　tunnel　movements　decrease　by　up　to　56.7%.　Moreover,　tunnel　movements　are　reduced　by　up　to　80.7%　and　61.3%,　respectively,　when　the　entire　depth　and　width　of　soil　within　basement　are　reinforced.　Installation　of　isolation　wall　can　greatly　reduce　tunnel　movements　due　to　adjacent　basement　excavation,　especially　for　tunnel　with　a　shallow　burial　depth.　The　effectiveness　of　isolation　wall　to　reduce　tunnel　movement　is　negligible　unless　the　wall　reaches　the　level　of　tunnel　invert.　©　2024　Techno-Press,　Ltd.