Subsurface　settlement　is　often　triggered　by　soil　erosion　above　underground　defective　pipelines.　However,　there　is　currently　insufficient　research　on　calculation　methods　for　estimating　ground　settlement　caused　by　defective　pipeline.　In　this　work,　a　series　of　laboratory　experiments　were　conducted　to　investigate　the　impacts　of　the　soil　particle　size,　hydraulic　gradient,　thick-span　ratio,　and　full　pipe　flow　velocity　on　ground　settlement　around　submerged　defective　pipelines.　A　sensitivity　analysis　was　performed　to　further　examine　these　factors.　The　experimental　results　revealed　that　there　are　three　settlement　modes,　primarily　determined　by　soil　skeleton　particle　size　and　the　thick-span　ratio.　.　The　full　pipe　flow　velocity　and　hydraulic　gradient　significantly　affected　the　settlement　range,　with　the　settlement　range　increasing　as　either　the　flow　velocity　or　hydraulic　gradient　increased.　Additionally,　a　new　calculation　model　based　on　Manning＇s　equation　was　developed　to　predict　soil　settlement.　The　error　between　the　calculation　and　experiment　results　was　less　than　15%,　demonstrating　the　accuracy　and　effectiveness　of　the　proposed　method.