Scour at Bridge Foundations on Rock (2012) / Chapter Skim
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Pages 162-166
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From page 162... ...
162 4.1 Applicability of Results to Highway Practice The Interstate Highway (I-90) Bridge over Schoharie Creek in New York failed during a flood in 1987 and led FHWA to issue a mandate for all highway bridges over water to be evaluated for scour-critical conditions.
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From page 163... ...
Conclusions, recommendations, and Suggested research 163 The time between flood events can contribute to reduction in scour resistance through weathering or slaking of rock materials, or enhanced circulation of water in joints held open by gravel fragments wedged into the joint planes during turbulent flow causing blocks of durable rock to vibrate or jostle. One of the most important conclusions of this research is that the scour resistance of degradable rock materials is not solely a function of the rock properties -- it is a rock-water interaction phenomenon.
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From page 164... ...
164 Scour at Bridge Foundations on rock value of 100 percent if the core is oriented parallel or perpendicular to the discontinuity planes. The same rock mass would have an RQD value of zero percent if the core is oriented 45 degrees to two of the discontinuity planes.
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From page 165... ...
Conclusions, recommendations, and Suggested research 165 Repeated cross sections are the best way to document scour. The cross sections used in this research posed some challenges for interpretation.
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From page 166... ...
166 Scour at Bridge Foundations on rock Progressive scour of degradable rock materials appears to be the most important rock-scour process on natural channels where bridges might be located. The results from the Sacramento River in Redding, California, are encouraging and indicate that the probability-weighted approach to defining the average annual scour is valuable.
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