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Research & Technology Transfer Alaska Department of Transportation & Public Facilities Research & Technology Transfer ALASKA DEPARTMENT OF TRANSPORTATION Impacts of Ice Forces on Stream Bank Protection Prepared by: Nathanael Vaughan, Jason Albert, Robert F. Carlson University of Alaska Fairbanks Fairbanks, Alaska 99775 August 2002 Prepared for: Alaska Department of Transportation Statewide Research Office 3132 Channel Drive Juneau, AK 99801-7898 FHWA-AK-RD-02-03 Form approved OMB No. 0704-0188 REPORT DOCUMENTATION PAGE Public reporting for this collection of information is estimated to average 1 hour per response, including the time for reviewing instructions, searching existing data sources, gathering and maintaining the data needed, and completing and reviewing the collection of information. Send comments regarding this burden estimate or any other aspect of this collection of information, including suggestion for reducing this burden to Washington Headquarters Services, Directorate for Information Operations and Reports, 1215 Jefferson Davis Highway, Suite 1204, Arlington, VA 22202-4302, and to the Office of Management and Budget, Paperwork Reduction Project (0704-1833), Washington, DC 20503 1. AGENCY USE ONLY (LEAVE BLANK) 2. REPORT DATE 3. REPORT TYPE AND DATES COVERED FHWA-AK-RD-02-03 August 2002 Final, September 2001 - August 2002 4. TITLE AND SUBTITLE 5. FUNDING NUMBERS Impacts of Ice Forces on Stream Bank Protection 6. AUTHOR(S) Nathanael Vaughan, Jason Albert, Robert F. Carlson 7. PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES) 8. PERFORMING ORGANIZATION REPORT NUMBER Department of Civil and Environmental Engineering University of Alaska Fairbanks Project No. 74687; RFP No. RES-01-011 PO Box 755900 Fairbanks AK 99775 9. SPONSORING/MONITORING AGENCY NAME(S) AND ADDRESS(ES) 10. SPONSORING/MONITORING AGENCY REPORT NUMBER State of Alaska, Alaska Dept. of Transportation and Public Facilities Research and Technology Transfer FHWA-AK-RD-02-03 2301 Peger Rd Fairbanks, AK 99709-5399 11. SUPPLENMENTARY NOTES Performed in cooperation with Research and Technology Transfer, State of Alaska Department of Transportation and Public Facilities. 12a. DISTRIBUTION / AVAILABILITY STATEMENT 12b. DISTRIBUTION CODE No restrictions 13. ABSTRACT (Maximum 200 words) At the request of the Alaska Department of Transportation and Public Facilities we quantitatively assessed the effects of five ice-related scenarios on riprap stability. Currently, a publication from the Federal Highways Administration, “Design of Riprap Revetment,” or HEC- 11, forms the design procedure for riprap under ice conditions. HEC-11 recommends a stability factor of 1.6-2.0 for ice impact specifically, but otherwise neglects ice influence on design. The five scenarios considered are riprap specific gravity reduction, raft ice impact, raft ice pushup, velocity increase beneath ice jams, and increased tractive stress due to ice cover. Stability factors for three of these conditions were then expressed in terms of the original HEC-11 stability factor, while two were expressed independently of the conditions considered in HEC-11. Generally, we found ice influence to be highly site specific and the limiting design variable for riprap revetment in northern rivers. 15. NUMBER OF PAGES 14. KEYWORDS : bank protective works, river protective works, riprap, revetments, ice formations, impact, stability analysis 74 16. PRICE CODE N/A 17. SECURITY CLASSIFICATION OF 18. SECURITY CLASSIFICATION 19. SECURITY 20. LIMITATION OF ABSTRACT REPORT OF THIS PAGE CLASSIFICATION OF ABSTRACT Unclassified Unclassified N/A Unclassified NSN 7540-01-280-5500 STANDARD FORM 298 (Rev. 2-98) Prescribed by ANSI Std. 239-18 298-1 Impacts of Ice Forces on Stream Bank Protection Final Report Prepared for Alaska Department of Transportation & Public Facilities Nathanael Vaughan Research Assistant Jason Albert Research Assistant Robert F. Carlson Professor and Chair Department of Civil and Environmental Engineering University of Alaska Fairbanks Fairbanks, Alaska 99775 Report No. FHWA-AK-RD-02-03 August 2002 Table of Contents Table of Contents ………………………………………………………………………….. ii List of Figures…………………………………………………………………..………….. iii List of Tables ……………………………………………………………………..……….. iv Acknowledgements ………………………………………………………...……………… v Abstract ……………………………………………………………………………………. vi Summary of Findings ………………………………………………………………..…….. 1 CHAPTER 1 - INTRODUCTION AND RESEARCH APPROACH……………..………. 2 Problem Statement ………………………………………………………………… 2 Objectives of the Study…………………………………………………………….. 2 Scope of Study……………………………………………………………………... 3 Research Approach………………………………………………………………… 3 CHAPTER 2 - FINDINGS………………………………………………………………… 4 State-of-the-Art Summary…………………………………………………………. 4 Analysis……………………………………………………………………………. 4 CHAPTER 3 - INTERPRETATIONS, APPRAISAL AND APPLICATIONS ..…………. 16 HEC-11 Considerations……………………………………………………………. 16 Review by Scenario………………………………………………………………... 16 CHAPTER 4 – CONCLUSIONS AND SUGGESTED RESEARCH.……………..……... 29 Conclusions………………………………………………………………………… 29 Suggested Research………………………………………………………………... 29 REFERENCES ……………………….……………..………………..…………………… 30 Cited References…………………………………………………………………… 30 Other References…………………………………………………………………… 31 Photo Credits………………………………………………………………………. 32 APPENDICIES ……………………………………………………...……………………. 34 Appendix A: Expanded Derivations………………………………………………. A1 ii Appendix B: Typical Values for Ice Properties……………………………………B-1 Appendix C: Alaska DOT&PF Workshop ………………………………………..C- 1 Workshop Summary………………………………………………………..C- 1 Workshop Agenda………………………………………………………….C- 3 Appendix D: Workshop Slides…………………………………………………….D-1 iii List of Figures Figure 2-1: Anchor ice diagram....…………..………………………………...………..… 8 Figure 2-2: Ice impact diagram…..……………………………………………...………... 9 Figure 2-3: Photo of ice shove onto riprapped shore………..……..………………….….. 11 Figure 2-4: Photo of ice jam on the Red Lake River, MN………...……………………… 13 Figure 2-5: Photo of break-up ice jam……………………...…….………………..……… 14 Figure 3-1: Graph of percentage of HEC-11 stability factor vs. void ratio…..…………… 17 Figure 3-2: Graph of percentage of HEC-11 stability factor vs. anchor ice depth divided by median riprap diameter..…………………………………………….....……… 17 Figure 3-3: Graph of critical axial stress vs. modulus of elasticity, ice..…………………. 19 Figure 3-4: Diagram of ice shove with ride-up…………………………..…………….….. 21 Figure 3-5: Schematic of ice accumulation in toe region…....…….……………...………. 23 Figure A-1: Illustration of ice saturation..………………………………………………… A2 Figure A-2: Anchor ice schematic……………………………………………...…………. A3 Figure A-3: Schematic of ice impact with bank...…………………………………………A5 iv List of Tables Table 1: Approximate stability factors: (Table 11, p. 145, HEC-11)……….…………….6 Table 2: Ice impact stability factor and median riprap size……………………………..20 Table 3: Ice shove & ride-up stability factor and median riprap size…...………………22 v Acknowledgements The research performed for this project was funded by the Alaska Department of Transportation and Public Facilities under Project No. FHWA-AK-RD-01-16. The work was performed at the Department of Civil and Environmental Engineering, University of Alaska Fairbanks, Fairbanks, Alaska with Dr. Robert F. Carlson, Professor and Chair, as the Principal Investigator. The project staff included Research Assistants Chad Hosier, Nathanael Vaughan, and Jason Albert. Clint Adler, Billy Connor and Mark Miles and other research section staff of AKDOTPF provided much appreciated contract management and critical review of the project reports. vi Abstract At the request of the Alaska Department of Transportation and Public Facilities we quantitatively assessed the effects of five ice-related scenarios on riprap stability. Currently, a publication from the Federal Highways Administration, “Design of Riprap Revetment,” or HEC-11, forms the design procedure for riprap under ice conditions. HEC-11 recommends a stability factor of 1.6-2.0 for ice impact specifically, but otherwise neglects ice influence on design. The five scenarios considered are riprap specific gravity reduction, raft ice impact, raft ice pushup, velocity increase beneath ice jams, and increased tractive stress due to ice cover. Stability factors for three of these conditions were then expressed in terms of the original HEC-11 stability factor, while two were expressed independently of the conditions considered in HEC-11. Generally, we found ice influence to be highly site specific and the limiting design variable for riprap revetment in northern rivers. vii Summary of Findings The objective of this research work was to provide engineering design information for the effects of river ice on riprap bank protection. The design manual for riprap, HEC-11, provides only rudimentary guideline for ice effects. The AKDOTPF designers, based on their experience, felt that more information is needed and the AKDOTPF research section commissioned this study. Paucity of Quantitative Design Criteria: We found very little information in past studies of the effects of ice on riprap bank protection. Other design manuals, including those published by the U.S. Army Corps of Engineers, and the USGS, treat ice forces with a less substantial and qualitative assessment than HEC-11. Most information was aimed towards ice pack shove in ocean environments. The little information on river ice environments was very qualitative and provides little useful design information. This reality led us to adopt an approach that uses fundamental mechanics and hydraulic principles to state the problem for
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