Existing railway and newly-built building ground combined construction device

The utility model relates to the technical field of railway construction, in particular to an existing railway and newly-built building ground combined construction device which comprises two protection arc plates, connecting grooves are formed in the opposite sides of the two protection arc plates, and connecting columns are arranged on the opposite sides of the two protection arc plates. When a worker needs to protect the overhead contact system of the existing railway, the worker firstly measures the height between the overhead contact system in the existing railway and the ground, then adjusts the supporting mechanisms to the corresponding specifications, and then moves the two sets of supporting mechanisms and the two protection arc plates to the two sides of the overhead contact system in the existing railway correspondingly; the two protection arc plates are connected together in a butt joint mode, the connecting columns are connected with the connecting grooves in an inserted mode, at the moment, even