Based　on　the　pile　active　underpinning　project　of　Xima　Bridge　in　Fuzhou　Metro　Line　I　shield　tunnel,　considering　the　complex　hyperstatic　structures　composed　by　bridge　superstructure,　bridge　piles　and　soil　masses,　the　numerical　simulation　and　the　field　monitoring　data　are　utilized　jointly　to　study　the　inner　force　and　displacement　responses　of　hyperstatic　structures　under　different　jacking　loads.　The　influences　of　superstructure　stiffness　and　substructure　stiffness　on　the　determination　of　jacking　load　are　emphasized.　The　reasonable　jacking　loads　for　two　typical　conditions　(the　piles　under　cap　beam　and　abutment　beam)　are　1　800　kN　and　2　600　kN　respectively,　which　make　the　axial　forces　of　underpinned　piles　reduce　to　zero.　The　field　monitoring　is　also　carried　out　during　construction,　and　the　displacement　of　bridge　superstructure　and　the　axial　force　of　bridge　pile　from　monitoring　data　are　consistent　with　their　counterparts　from　numerical　simulations.　Based　on　these　results　from　numerical　simulation　and　field　monitoring,　a　simplified　analytical　method　is　further　proposed　to　calculate　the　reasonable　active　jacking　load　by　considering　the　stiffness　ratio　between　the　superstructure　and　substructure,　which　can　provide　some　reference　for　the　pile　underpinning　projects　under　similar　scenarios.　©　2015,　Academia　Sinica.　All　right　reserved.