Abstract
Riprap protection works against local scour of sand bed are practical and effective if the riprap size is large enough and the protected bed sand is not drawn out through the riprap filter. These stability conditions were studies experimentally, and the results are applied for the design of multilayered filter protections with different riprap sizes to reduce the total thickness of the protection works. The critical ratio of riprap (D/d)c of riprap size D to bed sand size d for phisically possible movement of sand through riprap porosity was determined, and the damping of the tractive force through the riprap filter was expressed as a function of the ratio L/D of filter thickness L to the riprap size. And examples of practical design of the multilayered filter protections were shown.
