rock armour

plural rock armours · alternative rock armor

1. UKcountableuncountableRock or other suitable material used to protect shorelines, streambeds, bridge abutments, pilings and other structures against scour and water, wave, or ice erosion.

   Walk along the beach to where the rock armour begins, then join the sea wall[.]

   2019, Alan Staniforth, Cleveland Way, page 86

   1 more example

   Rock armour was first used on the line "in a very small way" after floods in 2005, and more extensively last year when an embankment had to be reinstated. "The destructive problem with flooding is when water washes over the railway and runs down the other side," explains Hinshelwood. "If it keeps coming, it starts to accelerate, to scour and create turbulence, picking up ever-larger material the faster it washes across. You can't stop it, but rock armour slows it to a point where it doesn't wash ballast or embankment material away."

   2020 August 26, Andrew Mourant, “Reinforced against future flooding”, in Rail, pages 59–60