Island-shaped permafrost region composite roadbed structure

The utility model provides a composite roadbed structure in an island-shaped permafrost region, which relates to the technical field of pavement foundations and comprises a foundation bed, a roadbed body, an anti-freezing layer, a mattress layer and a drainage ditch, the foundation bed comprises a foundation bed surface layer and a foundation bed bottom layer; the upper surface of the subgrade body is connected with a subgrade bed bottom layer, the subgrade body is in an isosceles trapezoid shape, first hot rods are arranged at the two waists of the isosceles trapezoid, and second hot rods are arranged at the slope toe of the isosceles trapezoid; the upper surface of the anti-freezing layer is connected with the lower surface of the roadbed body; the upper surface of the mattress layer is connected with the lower surface of the anti-freezing layer, the mattress layer is a broken stone hardcore, and a layer of bidirectional geogrid is laid in the broken stone hardcore. The plain concrete piles penetrate throug