2/9/2018 3:02:29 PM
10/7/2015 10:29:45 AM
WESTERN DAM ENGINEERING NEWSLETTER, VOLUME 3, ISSUE 3, JULY 2015
SPILLWAYS, DESIGN CONSIDERATIONS FOR OUTLET CONTROL, INSTRUMENTATION FOR SMALL EARTH DAMS
Document Type - Reference Library
Research, Thesis, Technical Publications
There are no annotations on this page.
Document management portal powered by Laserfiche WebLink 9 © 1998-2015
All rights reserved.
Pages to print
Enter page numbers and/or page ranges separated by commas. For example, 1,3,5-12.
After downloading, print the document using a PDF reader (e.g. Adobe Reader).
View plain text
<br /> <br /> <br /> <br />3 <br />of turbulent flow and erosion. Movement of larger particles requires higher velocities and or steeper slopes. <br />There are several methods available to assess the risks of spillway erosion. This article will present five of <br />the most common. Any spillway analysis for design or modification should be approached in more detail than <br />discussed below. The references at the end of this article provide more information for each method. <br />1. USACE Repair, Evaluation, Maintenance and Rehabilitation (REMR) <br />2. Cohesionless Soil <br />3. Annandale <br />4. Water Resources Site Analysis Program (SITES) <br />5. Computation Fluid Dynamics (CFD) <br /> <br />USACE REMR <br />The method developed by the USACE REMR is a qualitative classification of erodibility based on spillway <br />characteristics. The method predicts whether erosion is likely to occur but does not provide info rmation regarding the <br />extent or severity of erosion. The method involves assessing the erosion ‘risk’ as a function of spillway channel slope, <br />flow velocity and the effect of anomalies in the spillway geometry. Based on these characteristics, the spillway is <br />assigned an “A” rating as outlined below. <br />Soil or rock classification: <br />AAAA = Erosion-resistant rock <br />AAA = Moderately erosion-resistant rock <br />AA = Moderately erodible material <br />A = Erodible soil (nonvegetated) <br /> <br />Table 1: Erosion Risk Class <br />Spillway <br />Characteristic <br />Erosion Risk Class <br />AAAA AAA AA A <br />Slope (percent) 30-45 15-30 4-15 <4 <br />Flow velocity (ft/s) 10-15 7-10 4-7 <4 <br />Anomaly Effect Minor Moderate Major Severe <br /> <br />The erosion ‘risk’ is compared to the erosion ‘potential,’ which is based on geologic material behavior factors as shown <br />in Table 2. <br />Table 2: Erosion Potential Class <br />Spillway Characteristic Erosion Potential Class <br />AAAA AAA AA A <br />Lithology <br />Sandstone XXXXXXXXX XXXXXXXXX XXXXXXXXX X <br />Shale & Limestone X XXXXXXXXX XXXXXX <br />Limestone XXXXXXXXX <br />Granular Soil (Low PI) XXXXXXXXX <br />Cohesive Soil (High PI) XXXXXXXXX XX <br />Intrusive Igneous XXXXXXXXX <br />Extrusive Igneous XXXXXXXXX XXXXXXXXX XXXX <br />Massive Metamorphic XXXXXXXXX XXXXX <br />Foliated Metamorphic X XXXXXXXXX XXX <br />Substance <br />Density (pcf) >140 140-125 125-116 <116 <br />Uniaxial Strength (psi) >6000 6000-2000 2000-150 <150 <br />Genesis
The URL can be used to link to this page
Your browser does not support the video tag.