Prefabricated construction method for roadbed block stone layer in permafrost region

The invention discloses a permafrost region roadbed block stone layer assembly construction method which comprises the following steps: S1, screening out stone materials in a designed particle size range, assembling the stone materials into a plurality of block stone unit bodies, testing the porosity of the block stone unit bodies, and taking the particle size group ratio corresponding to the maximum porosity as the optimal particle size group ratio; assembling stones according to the optimal particle size group to form block stone unit bodies, and weighing the block stone unit bodies; s2, a lower bearing layer is constructed on the to-be-constructed site, and the laying positions of the block stone unit bodies are marked; s3, the block stone unit bodies are hoisted and compacted in sequence, and the porosity of the block stone layer is obtained; and S4, geotextile is laid on the block stone layer. By optimizing the proportion of the particle size groups, the porosity of the block stone layer of the roadbed c