Form Approved
REPORT DOCUMENTATION PAGE
OMB No. 0704-0188
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1. AGENCY USE ONLY (Leave blank)
2. REPORT DATE
3. REPORT TYPE AND DATES COVERED
April 1996
4. TITLE AND SUBTITLE
5. FUNDING NUMBERS
Ice Force and Scour Instrumentation for the White River, Vermont
CWP#32248
6. AUTHORS
Leonard J. Zabilansky
7. PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES)
8. PERFORMING ORGANIZATION
REPORT NUMBER
U.S. Army Cold Regions Research and Engineering Laboratory
72 Lyme Road
Special Report 96-6
Hanover, New Hampshire 03755-1290
9. SPONSORING/MONITORING AGENCY NAME(S) AND ADDRESS(ES)
10. SPONSORING/MONITORING
AGENCY REPORT NUMBER
State of Vermont
Federal Highway Administration
Montpelier, VT 05602
Washington, D.C.
11. SUPPLEMENTARY NOTES
12a. DISTRIBUTION/AVAILABILITY STATEMENT
12b. DISTRIBUTION CODE
Approved for public release; distribution is unlimited.
Available from NTIS, Springfield, Virginia 22161
13. ABSTRACT (Maximum 200 words)
In January 1990 a bridge over the White River in White River Junction, Vermont, collapsed during a period of ice
breakup. Based on the historic weather and stage data, the bridge had survived more dramatic breakups in
previous winters. The ultimate failure was attributed to the progressive deterioration of the foundation due to
scour. Twenty years of weather and stage data at the site are presented along with a failure scenario. Instrumen-
tation to measure the ice forces on a bridge pier was incorporated into the design of the replacement bridge.
Recognizing scour as the primary cause of failure, the new bridge piers have extensive scour protection. A pier
for a bridge 2000 feet upstream of the new bridge was instrumented for scour. The objective was to develop real-
time scour monitors that would survive ice and debris and allow correlation between the hydrograph and scour
activity. Instrumentation and data acquisition packages for both instrumented bridge piers are presented. The
results of the first two years of measurements are presented. Both winters were relatively mild, consequently the
breakup loads were low. The maximum dynamic load was 26 kips, which, with a 4-foot-wide panel and 12 inches
of ice translates to an ice pressure of 45 psi. The scour measurements were of extreme interest. The bulk of the scour
occurred in the initial stages of breakup while the ice sheet was still intact. Apparently to compensate for the fixed
ice surface, the mean velocity had to increase as the discharge increased. The faster velocity resulted in more
aggressive bed scour. Once the ice sheet broke up and the ice was free floating, the scour activity subsided.
14. SUBJECT TERMS
15. NUMBER OF PAGES
61
Ice forces
Scour
White River
16. PRICE CODE
17. SECURITY CLASSIFICATION
18. SECURITY CLASSIFICATION
19. SECURITY CLASSIFICATION
20. LIMITATION OF ABSTRACT
OF REPORT
OF THIS PAGE
OF ABSTRACT
UNCLASSIFIED
UNCLASSIFIED
UNCLASSIFIED
UL
Standard Form 298 (Rev. 2-89)
NSN 7540-01-280-5500
Prescribed by ANSI Std. Z39-18
298-102
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