Expansive soil cut slope support structure and construction method thereof

The invention relates to an expansive soil cut slope support structure and a construction method thereof, in particular to the field of highway and railway cut slope protection of expansive soil regions. The expansive soil cut slope support structure comprises a rigid supporting system, a flexible protection system and a waterproof and draining system. The rigid supporting system comprises a lame retaining wall arranged on an expansive soil cut slope and a retaining wall foundation; the flexible protection system comprises a lattice beam arranged on the expansive soil cut slope, an anchor rod, a flexible net-shaped geogrid laid on the slope surface and a plant cover planted on the slope surface; and the waterproof and draining system comprises an intercepting ditch or drainage ditch arranged at the top of the slope, a permeable layer positioned behind the retaining wall, a drainage ditch and a drainage seepage ditch positioned below the drainage ditch. The slope surface is supported through a flexible supporting system, and in comparison with a rigid supporting method of fully laying a mortar rubble structure on the slope surface, the construction cost is reduced by over 20%, and the construction period is greatly reduced; and expansive force generated when expansive soil is met with rainwater and expands can be effectively released.