Highway tunnel portal section collapsed mass slope protection reinforcing structure and construction method

The invention provides a highway tunnel portal section collapsed mass slope protection reinforcing structure. The highway tunnel portal section collapsed mass slope protection reinforcing structure comprises a tunnel, a step-shaped anchoring frame beam arranged on at least one side of the tunnel, a lower retaining wall, an end anti-slide pile and a long open cut tunnel. The stepped anchoring frame beam comprises multiple stages of frame beams distributed along a slope in a stepped mode, self-propelled anchor rods are arranged at lattice intersection points of the frame beams to be anchored to a mountain rock layer, net hanging grass planting protection is arranged in lattices, and net hanging spray ramming protection is arranged on a transition section between a tunnel upward slope and the multiple stages of frame beams. The lower retaining wall is an inclined retaining wall which is arranged at the toe of the side slope and inclines towards the side slope; the end anti-slide pile is arranged at the end of th