Combining Individual Scour Components to Determine Total Scour (2018) / Chapter Skim
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232 CHAPTER 6. Conclusions and Recommendations 6.1 Overview The objective of this research project is to determine the relationships among individual scour components observed in the same flow event at a bridge, and determine how to combine them to produce realistic estimates of total scour depth for safe and economical design of bridge foundations.
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233 6.2 Conclusions The aims of this investigation were satisfied successfully by dividing scour interactions into four categories and developing predictive equations for each type of interaction as shown previously in Table 4-7. The categories are related to the abutment length (long setback abutment (LSA)
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234 intended in the research plan. A separate equation for Category II CWS scour prediction was developed, but it was of the same form as the Category I equation with the backwater ratio neglected because of the larger depths in the main channel.
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235 contrast to using the approach flow velocity ratio and the relative vertical geometric contraction ratio. Some previous investigators have also formulated vertical contraction scour alone in terms of flow intensity under the bridge.
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236 secondary currents that might be generated in a bend upstream of a bridge. Furthermore, the 2D RANS model was demonstrated to perform well when applied to a field example at prototype scale.
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237 turbulence closure and including submerged orifice and overtopping flows as well as free flows for estimating scour prediction parameters; Extend current riprap protection design procedures for embankments and riprap aprons to include more energetic submerged orifice and overtopping flows, especially in live-bed scour; Commit to a long-term scour monitoring program at bridges to obtain a more robust set of field data for model validation at a wide variety of bridges.
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