The Effect of a Stabilized Stone Drainage Layer on ACB Performance in Open Channel Flow Applications

This paper will document and discuss the results of full scale flume testing of a tapered ACB(articulating concrete block)system utilizing a stabilized stone drainage layer(Shoretec EPEC)under both steady state and hydraulic jump induced flow conditions.Articulated Concrete Block revetment systems have documented performance improvement when a stone drainage layer is included under the blocks,which was initially discovered in the late 1990’s and has largely remained an unstudied area of ACB testing for the past 25 years.In 2010,testing of a tapered ACB system was conducted in which the length of the test section was increased from 12.2 m to 21.3 m with a 10.2 cm thick stone drainage layer resulting in no apparent issues with the movement of the drainage layer.In 2013,more flume testing was conducted on a tapered ACB system in which the test section was increased from 21.3 m to 30.5 m and the stone drainage layer was increased from 10.2 cm to 15.2 cm.The results of this test showed significant ACB block movement at the 0.91,1.22 and 1.62 m OT(overtopping depth)depths,in some instances exceeding 6.35 cm.In 2017,a 27.4 m test flume was constructed for a tapered ACB system(Shoretec EPEC)utilizing 15.2 cm of stone as a drainage layer with a 3-dimensional load platform added for stone stabilization.The results of this test run showed that,at 1.62 m of OT depth,ACB block movement was kept to under 16 mm in the vertical and hydraulic jump stability was attained up to the maximum discharge flow of 2.579 m3/s/m on a 2:1 slope.Using the new design data,graphs will be presented showing the new range of hydraulic conditions now suitable for ACB tapered revetment systems with a stabilized stone drainage layer.In addition,design criteria necessary for the successful deployment of the 3-dimensional transfer platform system will be presented.