Formed tunnel expanding equipment and construction method thereof

The invention discloses expanding equipment for a formed tunnel. The expanding equipment comprises a main body frame, a walking mechanism, a tunnel supporting mechanism, a soil body protection device, a pipe piece dismounting and mounting device, a soil body excavation device and a muck transportation device. Wherein the walking mechanism is arranged at the bottom of the main body frame and used for driving the main body frame to walk; the tunnel supporting mechanism is arranged on the main body frame and is used for tightly supporting a duct piece above an excavated soil body or the inner wall of a tunnel; the soil body protection device is arranged on the main body frame and used for supporting the soil body outside the excavation face; the duct piece disassembling and assembling device is arranged on the main body frame and used for disassembling and assembling duct pieces; the soil body excavation device is arranged on the main body frame, located between the pipe piece dismounting and mounting device and