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Advancements in the Design of Articulated Concrete Block Mats. Joe Kerrigan, P.E . (CO) Basalite Concrete Products LLC. Action Items for TODAY. During this presentation we will introduce: National Concrete Masonry Association (NCMA) Articulated Concrete Block Mat (ACBM) design manual.
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Advancements in the Design of Articulated Concrete Block Mats Joe Kerrigan, P.E. (CO) Basalite Concrete Products LLC
Action Items for TODAY • During this presentation we will introduce: • National Concrete Masonry Association (NCMA) Articulated Concrete Block Mat (ACBM) design manual. • Review Factor of Safety method of design and provide design spreadsheets for analysis and design of these systems
Goals for TODAY • Show How these approaches can add value to your projects • Show How these are cost effective approaches
Erosion takes place when the flow conditions exceed the limits of natural vegetation
Erosion Control Issue Low Level High Level Low Velocity High Velocity (ft/s) The Performance Pyramid
Cable Sleeves Blocks Ultra Flex System Components Washers Ultra Flex System Components
Up to 8’ Up to 40’ The Ultra Flex System…virtually any size you want
Open Cell Blocks for applications where vegetation is desired Closed Cell Blocks for applications where you may not want as much vegetation The Ultra Flex System…for vegetation or minimal vegetation
Place and Lace When ACCESS MATTERS
Channelized Flow Scenario Wave-Attack Scenario Overtopping Flow Scenario Understanding the Design Hydraulic Conditions
The Factor-of-Safety Methodology for ACB’s • "Erosion and Sedimentation" by Pierre Julien, Cambridge University Press, 1995” • SF = ((2 / 1) ) / ((1 - 2)0.5 cos + (2 / 1) + (3 Fd’ cos + 4 Fl’) / 1Ws) When one block loses intimate contact with the underlying subgrade…this will constitute a system failure. Factor-of-Safety Methodology
1 Block Overtopping Tests Flume Setup 2 3 It all starts with Hydraulic Testing
Block Overtopping Tests Data Acquisition It all starts with Hydraulic Testing
Block and Geotextile is Removed Shear Stress Can Be Calculated L1,L2, L3 and L4 (inches or mm) Critical Sear Stress is determined from this testing and can be used to determine the shear stress from thicker units
Flow Fi FL FD FG1 FG2 FR Destabilizing Forces Fi = Impact force (projecting block) FL = Lift Force FD = Drag Force FG1 = Gravity force parallel to slope Stabilizing Forces FR = Interblock resistance FG2 = Gravity force normal to slope Destabilizing vs. Stabilizing Forces
Picking the “Right” Unit given the Factor-of-Safety Methodology
4.5 inches 6.0 inches 9.0 inches System Performance Increases as the Unit Weight (Thickness) Increases Variety of Thicknesses
Block data Channel data Given the Same Channel and Hydraulic Input Parameters
Riprap • D50 Weight = 863 lbs • D50 Diameter = 28 in • Layer Thickness = 60 in ACB/M 6” Unit And the Winner Is…
Action Items for this information • NCMA Manual and Design Spreadsheets • Please contact Joe Kerrigan at joseph.kerrigan@paccoast.com • Please include your name • Physical Address and e-mail address