Tunnel siphon drainage system

The utility model provides a tunnel siphon drainage system, which belongs to the technical field of tunnel engineering construction and comprises a drainage pipe, a water replenishing vertical pipe, a construction high-pressure water pipe, a water replenishing control valve, a one-way exhaust valve, a one-way check valve, a drainage control valve, a floating ball, a floating ball rotating rod, a floating ball support, a water level control switch, a switch pull wire and a switch support. A water pump does not need to be installed, water pumping and drainage are conducted through the siphon effect, a large amount of water pump purchase and maintenance cost and electricity charge are saved, and the problem that water overflows out of a pump station and flows back due to water pump faults is solved. A conventional power system does not need to be connected, and the solar cell panel is used for supplying power, so that risks such as hole flooding caused by sudden power failure are avoided; according to the water