Marcel van Gent, Gregory M. Smith, Ivo van der Werf


The stability of rock slopes with a horizontal berm has been studied by means of physical model tests. This paper is focussed on the rock slope stability of the slopes above and below the berm. By applying a berm the rock size can be reduced compared to the required rock size for a straight slope without a berm. This reduction can be significant for the slope above the berm. The influence of the slope angle (1:2 and 1:4), the width of the berm, the level of the berm, and the wave steepness have been investigated. Based on the test results prediction formulae have been derived to quantify the required rock size for rubble mound breakwaters with a berm.


coastal structures; breakwaters; rock slopes; stability; berm; physical model tests; design formula

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Dijkstra, O.P.J. 2008. Armour stability on a bermed slope breakwater, M.Sc. thesis, Delft University of Technology.

Mansard, E. and E. Funke. 1980. The measurement of incident and reflected spectra using a leastsquare method, Proc. ICCE'80, ASCE, pp.154-172.

Rock Manual. 2007. The use of rock in hydraulic engineering (2nd edition), CIRIA, CUR, CETMEF, Published by C683, CIRIA, London (ISBN 978-0-86017-683-1 and 5).

Van der Meer, J.W. 1988. Rock slopes and gravel beaches under wave attack, Ph.D. thesis, Delft University of Technology.

Van Gent, M.R.A. 2001. Wave run-up on dikes with shallow foreshores, Journal of Waterway, Port, Coastal and Ocean Engineering, ASCE, Vol.127, No.5, Sept/Oct 2001, pp.254-262.

Van Gent, M.R.A., H.F.P. Van den Boogaard, B. Pozueta and J.R. Medina. 2007. Neural network modelling of wave overtopping at coastal structures, Coastal Engineering, Elsevier, Vol.54, pp. 586-593.

Van Gent, M.R.A., A. Smale and C. Kuiper. 2003. Stability of rock slopes with shallow foreshores, Proc. Coastal Structures conference 2003, Portland, USA.

Van Gent, M.R.A. 2004. On the stability of rock slopes, Balkema, Keynote, Proc. NATO-Workshop on Environmental friendly coastal protection structures, Varna, Bulgaria.

Van Gent, M.R.A., G.M. Smith and I.M. Van der Werf. 2011. Stability of rock slopes with a berm: The upper slope, Proc. Coastal Structures conference 2011, Yokohama, Japan.

Vermeer, A.C.M. 1986. Stability of rubble mound berms and toe constructions; report on literature survey and model investigation (in Dutch), Delft Hydraulics Report M2006, Delft.