Combined construction of newly-built tunnel and existing bridge and construction method thereof

The invention provides a newly-built tunnel and existing bridge combined building structure and a construction method thereof.The combined building structure is formed by conducting in-situ underpinning on an existing bridge and then conducting combined building on the existing bridge and the newly-built tunnel, and piers of the bridge are replaced by newly-built piers to be arranged on a bridge and tunnel combined building bearing platform of a newly-built tunnel concrete structure; and a bridge and tunnel shared reinforcing pile foundation is arranged below the newly-built tunnel concrete structure. Therefore, according to the bridge and tunnel combined construction structure and the construction method thereof, the permanent occupied space is small, the manufacturing cost is saved, and the existing bridge and the newly-built tunnel can be jointly constructed and arranged at the same position at the cross joint. 本发明提供了一种新建隧道与既有桥梁合建构造及其施工方法，所述合建构造通过将既有桥梁原位托换后与新建隧道合建形成，所述桥梁的桥墩置换为新建桥墩设置在新建隧道混凝土结构的桥隧共建承台上，所述新建隧