Roadbed reconstruction mode based on existing road

The invention relates to the technical field of roadbed reconstruction, in particular to a roadbed reconstruction mode based on an existing road, which comprises the following steps: S1, burying a drainage pipe in a drainage channel of a cement layer, reserving a branch pipe, and pouring a concrete layer in the drainage channel to fix the drainage pipe; s2, a base layer is poured on the cement layer, a mounting cavity is formed in the top of the base layer, a plurality of drainage tanks are placed in the mounting cavity, the drainage tanks are provided with water guide grooves, and the water guide grooves communicate with the branch pipes; s3, an anti-cracking layer is poured on the base layer; s4, an asphalt layer is poured on the anti-cracking layer; and S5, curbs are arranged on the two sides of the asphalt layer in the width direction of the road. The installation cavity is formed in the base layer, the drainage tank is embedded in the installation cavity and communicated with the drainage pipe, water inf