Evaluation of Bridge-Scour Research: Abutment and Contraction Scour Processes and Prediction (2011) / Chapter Skim
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APPENDIX C
APPENDIX C
Pages 87-93
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From page 87... ...
They can be used to develop project scope and objectives. C.2 RESEARCH REGARDING ABUTMENT-SCOUR PROCESSES The ensuing problem statements elaborate the research needs in Table 8-1.
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From page 88... ...
The abutment column typically remains standing. Because spill-slope failure increases the flow area through a bridge waterway, and deposits material in the scour area, the maximum scour depth attainable at an abutment, and damage sustained by an abutment, appears to be limited by the geotechnical stability of an abutment's earthfill embankment.
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From page 89... ...
It is essential to pinpoint the flow conditions for which maximum scour depth occurs in order to develop an assessment of the vulnerability of existing bridges to failure and to devise design criteria for new bridges under climate change scenarios. Research Need FS1: Field studies with continuous hydraulic and scour monitoring that assess uncertainties in measurement and that can be compared with laboratory physical models Simultaneous measurement of bed elevations and the flow field are possible with in situ sensing devices that record the data and transmit it for real-time bridge monitoring on the internet .
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From page 90... ...
The two methods have similarities in formulation and prompt the question as to whether they could be developed further as a single method better reflecting improved understanding of scour as amplification of abutment scour. This research effort entails additional critical review of the two methods, and transition to an updated method to be validated using laboratory and field data.
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From page 91... ...
Accordingly there is a need to determine how the leading methods for estimating abutment scour depth apply during pressure scour situations. When feasible, conduct diagnostic field studies to determine method veracity.
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From page 92... ...
Estimation of the peak magnitudes of flow velocity, boundary shear stress, and unit discharge is of substantial importance for design estimation of scour at bridge abutments. Research also is needed to show how abutment flow fields adjust in response to variations of abutment length, floodplain width, and main channel dimensions, and identify trends regarding the magnitude of amplification factors for depth-averaged velocity, unit discharge, bed shear stress, and distance to peak unit discharge.
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From page 93... ...
In line with problem statement IF1, there is a similar need for instrumentation for monitoring embankment soil condition during flood hydrograph passage. Information from such instrumentation will assist diagnostic analysis of embankment failure during abutment scour.
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