Cold joint waterproof structure suitable for tunnel engineering construction in cold region

A cold joint waterproof structure suitable for tunnel engineering construction in a cold region comprises a first concrete structure, a second concrete structure, a connecting layer and a steel bar fixing structure. A connecting layer is arranged at a construction joint interface of the first concrete structure and the second concrete structure, a supporting device is arranged in the connecting layer, and the connecting layer is filled with a functional material; waterproof protection structures are arranged at the two ends of the connecting layer; the waterproof protection structure comprises a coating layer and a protection layer, the coating layer is coated with a waterproof layer, and a lining heat insulation layer is laid in the protection layer; the waterproof protection structures at the two ends of the connecting layer play a role in preventing water, play a role in protecting the connecting layer and play a role in preserving heat; the supporting device arranged in the connecting layer stretches to p