Tunnel liquid drainage system and construction method thereof

The invention relates to a tunnel liquid drainage system. The tunnel liquid drainage system comprises a water pump and drainage channels arranged on the two sides of a tunnel pavement, and further comprises a filtering device. The filtering device comprises a cylinder and a filtering plate. The filtering plate is arranged at the top of the cylinder. The water pump comprises a suction pipe and a drainage pipe. The water pump drives the suction pipe to suck water in the drainage channels and drain the water into the cylinder through the drainage pipe. The filtering plate is used for filtering the water entering the cylinder. The bottom end of the cylinder communicates with a drainage pipe. The drainage pipe drains the water in the cylinder into the external environment. The water pump drives the suction pipe to suck sewage in the drainage channels, then the sewage is filtered through the filtering plate and drained into the cylinder, finally the filtered water in the cylinder is drained to the outside through t