| 1. Report No. A450, A464 |
2. Government Accession No. |
3. Recipient's Catalog No.
|
4. Title and Subtitle Analysis of Effects of Deep Braced Excavations on Adjacent Buried Utilities |
5. Report Date December, 2003 |
6. Performing Organization Code |
7. Author/s Richard J. Finno, Kristin M. Molnar, Edwin C. Rossow |
8. Performing Organization Report No. |
9. Performing Organization Name and Address
Department of Civil and Environmental Engineering
Northwestern University
2145 Sheridan Road
Evanston, IL 60208 |
10. Work Unit No. (TRAIS) |
11. Contract or Grant No.
DTRS98-G-0016 |
12. Sponsoring Organization Name and Address
U.S. Department of Transportation
Research and Special Programs Administration
400 7th Street, SW
Washington, DC 20590-0001 |
13. Type of Report and Period Covered Final Report, April 1, 2002 – September 30, 2003 |
14. Sponsoring Agency Code |
15. Supplementary Notes |
16. Abstract Ground movements resulting from deep braced excavations impose the risk of damage to adjacent buried pipelines. Accurate assessment of the effects these movements have on pipelines allows potential damage to be avoided or mitigated. A predictive process for determining the stresses occurring in a pipeline adjacent to deep braced excavations is presented. The method can be used to establish rational criteria for determining allowable maximum values for excavation-induced ground movements. The ground movement distribution around the excavated area is predicted using a complimentary error function, an assessment of the maximum ground deformation, and knowledge of the geometry of the excavation. The pipeline is assumed to move with the ground enabling the behavior of the pipeline to be represented by the ground surface movements at its location. Conservative analyses for determining the bending stresses and joint rotations along a pipeline caused by its deformation are established. Allowable values for both the tensile bending stress and joint rotation resulting from the excavation-induced movements are presented for comparison with the computed maximum values. The predictive methodology is applied to three gas mains surrounding a deep braced excavation in downtown Chicago and four cast iron mains from various excavations in Chicago. For these cases, the calculated bending stresses in the pipelines were significantly smaller than allowable values, but the joint rotations were observed to be the more critical case. |
17. Key Words Excavation, Pipelines, Deformation, Seismicity, Infrastructure |
18. Distribution Statement No Restrictions |
19. Security Classification (of this report) Unclassified |
20. Security Classification (of this page) Unclassified |
21. No. Of Pages 168 |
22. Price |
