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<br />Seal around Pier:
<br />Research conducted by the FHWA has indicated that the space between the pier and the
<br />cable-tied concrete blocks must be filled or scour may occur under the blocks. To provide
<br />this seal, MnDOT proposed that concrete be placed around the pier. MnDOT suggested
<br />that the river bed could be excavated around the piers to the top of the footing. The mat
<br />could be put directly on top of the footing and next to the pier with concrete placed
<br />underneath, on top of, or both, to provide a seal between mat and pier.
<br />
<br />The State of Maine Department of Transportation (MOOT) has designed an articulated block
<br />system for a pier at Tukey's Bridge over Back Cove. MOOT recommended a design in
<br />which grout bags were placed on top of the mat at the pier location to provide the necessary
<br />seal (see Figure 4.7).
<br />
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<br />
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<br />
<br />Figure 4.7 Design plans of cable-tied precast block mat for Tukey's Bridge, ME
<br />(MOOT)
<br />
<br />References
<br />
<br />Brown, SA, E.S. Clyde, 1989, "Design of Riprap Revetment," Hydraulic Engineering
<br />Circular No. 11, FHWA-IP-016, prepared lor FHWA, Washington, D.C.
<br />
<br />Clopper, P.E., 1992, "Protecting Embankment Dams with Concrete Block Systems," Hydro
<br />Review, Vol. X, No.2, April.
<br />
<br />Clopper, P.E., 1989, "Hydraulic Stability of Articulated Concrete Block Revetment Systems
<br />During Overtopping Flow," FHWA-RD-89-199, Office of Engineering and Highway
<br />Operations R&D, McLean VA.
<br />
<br />Clopper, P.E., V. Chen, 1988, "Minimizing Embankment Damage During Overtopping Flow,"
<br />FHWA-RD-88-181, Office of Engineering and Highway Operations R&D, McLean VA.
<br />
<br />4.15
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