Definition of shore up phrasal verb from the Oxford Advanced Learner's Dictionary

Phrasal Verbs
  1. 1to support part of a building or other large structure by placing large pieces of wood or metal against or under it so that it does not fall down Timbers were used to shore up the tunnel. See related entries: Historic buildings, Structures
  2. 2to help to support something that is weak or going to fail The measures were aimed at shoring up the economy.
See the Oxford Advanced American Dictionary entry: shore up