Assessment Of Stability and Energy Dissipation Performances of an Antifer Layer Protected Caisson

Abstract

The present study intends to assess the stability and energy dissipation performances of a breakwater configuration (APC) protected by an antifer layer. For comparison, an ordinary caisson (OC), which was 5% wider and 10% heavier, was also investigated. Physical models were implemented and tested under regular and irregular waves; and resulting linear and angular displacements were directly measured via a photogrammetric method. Additionally, wave forces and resulting horizontal displacements were estimated both from recorded pressure data and from individual incident waves by modified Goda method. To calculate the horizontal displacement, the estimated wave force time series were directly double-integrated, whilst the theoretical method proposed by Shimosako et al. (1994) were used on the individual force values. Although OC was tested under shorter durations and had a more favorable superstructure in terms of resisting forces, the results indicated that APC was significantly more stable. Energy dissipation performance of the tested configurations were quantified in terms of spectral averaged and phase resolved reflection coefficients, whereas antifer damage ratio was measured on a block-count basis. Results indicated that the APC configuration had an enhanced performance of dissipating the wave energy; moreover, the dissipated energy directly links to antifer damage ratio.

Keywords

• Antifer protected caisson,Caisson displacements,Stability performance,Damage ratio,Wave energy dissipation

References

1. CEM Coastal Engineering Manual (2006) U.S. Army Corps of Engineers, Washington, D.C.
2. Goda, Y. (1967) “The fourth order approximation to the pressure of standing waves,” Coastal Engineering in Japan, 10, 1–11.
3. Goda, Y. (1985) “Random seas and design of maritime structures”, University of Tokyo Press, Japonya.
4. Goda Y. (1994) “Dynamic response of upright breakwater to impulsive force of breaking wave,” Coastal Engineering, 22(1,2), 135 –158.
5. Goda Y. (2008) “Lecture notes of seminar on recent developments in coastal engineering by Prof. Y. Goda”, 21-22 May 2008, METU Cultural & Convention Centre, Ankara.
6. Goda Y. (2010) “Reanalysis of regular and random breaking wave statistics,” Coastal Engineering Journal, 52(1), 71-106.
7. Kim, T-M & Takayama T. (2003) “Computational improvement for expected sliding distance of a caisson-type breakwater by introduction of a doubly-truncated normal distribution,” Coastal Engineering Journal, 45(3), 387– 419.
8. Kirca, V.S.O (2008) “Effect of frontface configuration on the performance of vertical faced coastal structures,” PhD Thesis, Coastal Sciences and Engineering Programme, Institute of Sci. & Tech., Istanbul Technical University, Istanbul.

9. Kirca, V.S.O. & Kabdasli, M.S. (2009) “Reduction of non-breaking wave loads on caisson type breakwaters using a modified perforated configuration,” Ocean Engineering, 36, 1316-1331.
10. Kirca, V. S., Kabdasli, M. S., Seker, D. Z., & Celikoyan, M. (2013) “Stability and Energy Dissipation of an Antifer Layer Protected Caisson.” In The Twenty-third International Offshore and Polar Engineering Conference, ISOPE 2013, June 30-July 5, Anchorage, AL, USA.
11. Ling, H.I., Cheng, A. H.-D., Mohri,Y & Kawabata, T. (1999) “Permanent displacement of composite breakwaters subject to wave impact,” J. Wtrwy. Port, Coast., and Oc. Engrg., ASCE, 125(1), 1–8.
12. Liu, P.L.-F., Lin, P., Chang, K.-A. & Sakakiyama T. (1999) “Numerical modeling of wave interaction with porous structures,” J. Wtrwy. Port, Coast., and Oc. Engrg., ASCE, 125(6), 322–330.
13. NAVFAC (Naval Facilities Engineering Command) (1986) “Design Manual DM7-02: Foundations and Earth Structures”, p. 7.2-63, Virginia.
14. Oumeraci, H. (1994) “Review and analysis of vertical breakwater failures—lessons learned,” Coastal Engineering, 22, 3–29.
15. Oumeraci H. & Kortenhaus A. (1994) “Analysis of the dynamic response of caisson breakwater,” Coastal Engineering, 22(1; 2): 159 –183.
16. Sakakiyama T. & Liu, P.L.-F. (2001) “Laboratory experiments for wave motions and turbulence flows in front of a breakwater.” Coastal Engineering, 44, 117–139.
17. Shimosako, K, Takahashi, S. & Tanimoto, K. (1994) “Estimating the sliding distance of composite breakwaters due to wave forces inclusive of impulsive forces,” in Proceedings of 24th ICCE, ASCE: 1580-1594.
18. Shimosako, K. & Takahashi, S. (1999) “Application of deformation based reliability for coastal structures,” in proceedings of Coastal Structures ’99, p.363-371, (ed.) Losada, Balkema, Rotterdam.
19. Sørensen, J.D. & Burcharth, H.F. (2000) “Reliability analysis of geotechnical failure modes for vertical wall breakwaters,” Computers and Geotechnics, 26, 225-245.
20. Takahashi., S., Tanimoto, K., & Shimosako, K. (1990) “Wave and block forces on a caisson covered with wave dissipating blocks,” Report of Port and Harbour Research Institute, Yokosuka, Japan, Vol 30, No. 4, pp 3-34 (in Japanese).
21. Takahashi, S., Tanimoto, K. & Shimosako, K. (1994) “A proposal of impulsive pressure coefficient for the design of composite breakwaters,” in proceedings of Hydro-Port’94, vol. 1., Port and Harbour Research Institute, Yokosuka, 489– 504.
22. Walkden, M.J., Wood, D.J., Bruce T. & Pregrine, D.H. (2001) “Impulsive seaward loads induced by wave overtopping on caisson breakwaters,” Coastal Engineering, 42, 257-276.
23. Wang Y, Hua L & Dong S. (2004) “Dynamic model of vibrating-sliding-uplift rocking coupled motion and dynamic design method of caisson breakwaters,” Science in China, Series E, 34(3), 564 –576.
24. Wang Y., Chen N.N. & Chi L.H. (2006) “Numerical simulation on joint motion process of various modes of caisson breakwater under wave excitation,” Communication in Numerical Methods in Eng’g, 22, 535-545.
25. Yagci, O., Kapdasli, S & Cigizoglu, H.K. (2004) “The stability of the antifer units used on breakwaters in case of irregular placement,” Ocean Engineering, 31, p. 1111–1127.