Instability of rock-fill spur-dykes in mountainous rivers and countermeasures

Abstract

Rock-fill spur-dykes are often destroyed due to rapid flows in mountainous rivers. On the basis of laboratory work in a flume, this paper describes the instability of rock-fill spur-dykes qualitatively, analyzing the classification of direct damage and indirect damage, respectively, and some main influencing factors as well, also summarizes countermeasures against the instability. Furthermore, the analyses of turbulent flow around the spur-dyke and its role on the riprap protection are performed, accordingly the layout of geotextile soft mattress as a countermeasure is determined. Observations on the entrainment of the top stones show that dune-shaped rock-fill spur-dyke improves the stability of rock, and therefore modification in cross-section of spur-dykes is proposed as a countermeasure against the direct damage.