#Concrete flume with energy dissipators manuals

The design procedure accounts for additional forces applied to the unit when protrusions above the matrix occur, such as subgrade irregularities or due to improper placement (see Figure 3). This ratio defines the factor of safety against uplift. The size and weight of the ACB units, as well as performance data from full-scale laboratory testing, are considered in evaluating the ratio of resisting to overturning moments (the “force balance” approach). For cases where the revetment is placed on steep side slopes (2H:1V or steeper), the design should evaluate the potential for slip shear failures along geosynthetic-ACB unit interfaces induced by hydraulic and gravitational forces (i.e., potential slope instability).įundamental principles of open channel flow and rigid body mechanics are used along with hydraulic test results supplied by manufacturers. The revetment system is more apt to fail as a result of overturning about the downstream edge of the ACB unit, or downstream corner point when the ACB unit is located on the side slope of a steep channel. In typical channel and spillway applications, failure due to sliding (slipping) of the ACB revetment along the bed is remote. The design method involves balancing the driving and resisting forces, including gravity, drag and lift as illustrated in Figure 2. Similar to many rip rap sizing methods, the Factor of Safety method quantifies hydraulic stability of ACB systems using a “discrete particle” approach (see ref.

#Concrete flume with energy dissipators manuals

These topics are covered in design manuals such as references 5 and 6. This TEK does not address geotextile filter and/or subgrade filter design, minimum installation guidelines critical to the proper performance of ACB revetments, or minimum upstream or downstream toe treatments. This TEK addresses the structural stability of ACB revetment systems as a function of site-specific hydraulic conditions and unit characteristics. Units must conform to minimum compressive strength, absorption and geometric specifications tested in accordance with Standard Test Methods for Sampling and Testing Concrete Masonry Units and Related Units, ASTM C140 (ref. Figure 1 illustrates a variety of ACB systems, but is not all-inclusive of available systems.ĪCB units are concrete block produced in accordance with Standard Specification for Materials and Manufacture of Articulating Concrete Block (ACB) Revetment Systems, ASTM D6684 (ref.

Systems with openings in the blocks can typically be vegetated to provide a “green” channel and facilitate infiltration/exfiltration of channel moisture. Systems may be connected through geometric interlock and/or other components such as cables. Because it is composed of individual units, the ACB system can conform to minor changes in the subgrade without loss of intimate contact. ACB systems are a matrix of individual concrete blocks placed closely together to form an erosion-resistant overlay with specific hydraulic performance characteristics. Articulating concrete block (ACB) systems provide erosion protection to soil exposed to the hydraulic forces of moving water. This TEK is intended to help designers understand the ACB design methodology and the different variables influencing the design and safety factor selection.