Reinforcement device for tunnel top soil and construction method thereof

The invention relates to a reinforcement device for tunnel top soil and a construction method thereof. The reinforcement device comprises an injection pipe and a water stopping device. A water stopping pipe is arranged in the water stopping device. The injection pipe is formed by a plurality of sections of metal circular pipes. The metal circular pipes are connected by using specially-shaped connecting components. An injection hole is arranged on the injection pipe. One end of the injection pipe is connected with a tapered bit and the other end of the injection pie is connected with a ball valve. A fixed circular plate is arranged on the external side of the water stopping pipe. A flange with a rubber sealing gasket is arranged at one end of the water stopping pipe. The water stopping device is fixedly installed in a pre-drilled hole at the top of a tunnel to prevent underground water from seeping into the tunnel from the water stopping pipe. After the injection pipe is punched into soil at the top of the tunnel through the water stopping device, a low-pressure pump is used to inject grout into the injection pipe. The grout fills the gaps in the soil at the top of the tunnel under the effect of gravity to form high-strength low-permeability bonded rocks. Thereby, the bearing capacity of the foundation is improved and the potential safety hazards caused by loose soil above the tunnel to the top of the tunnel are eliminated.