SEABED INSTABILITY AROUND CAISSON BREAKWATERS

Gerardo Duran, Juan Manuel Mayoral, Edgar Mendoza, Rodolfo Silva

Abstract


A sensibility numerical study, considering the soil conditions found at Frontera Port in Tabasco, Mexico was conducted to identify the variables that govern the response of a seabed-foundation-structure system subject to wave loading. Among all the possible causes of instability, this study deals only with those associated with liquefaction failure of silty-sands due to cyclic shear stresses generated by regular waves. This research was prompted by the accidents that have occurred near Frontera Port, the most serious of which took place in October 2007 when the Usumacinta oil platform settled, causing 21 fatalities. Previous analysis of this accident (Leis, et al, 2007) suggested that the platform did not present any structural failure and that the accident was a result of an unexpected behavior of the seabed; probably liquefaction. In order to offer results regarding coastal protection activities in the study area, the analysis presented here was developed simulating a vertical breakwater similar to that constructed in 2001 at Barcelona instead of the oil platform. Puzrin, et al, 2009 report that in November 2001 four caissons of this breakwater failed due to seabed liquefaction. The adaptation of the design of the vertical breakwater to the study area conditions was estimated by means of the Goda, 1985 formula.

Keywords


seabed; liquefaction; breakwaters

References


•Brebner, A. and Donnelly, D., 1962. "Laboratory Study of Rubble Foundations for Vertical Breakwaters." Proc. 8 th ICCE. New Mexico City, pp. 406-429.

•Goda, Y. 1973. "A New Method of Wave Pressure Calculation for the Design of Composite Breakwater." Rept. Port and Harbour Research Institute, Vol. 12

No. 3, pp. 31-70 (in Japanese); Proc. 14th ICCE 1974, Copenhagen, Denmark, pp. 1702-1720.

•Leis, B., et al. 2007. Root Cause Analysis of the Usumacinta-KAB-101 Incident, Battelle's Energy Systems, Columbus, OH,USA.

•Puzrin, A.M., Alonso, E.E. and Pinyol, N. (2010), "Geomechanics of Failures", Springer, Amsterdam, pp. 87-146 pp.

•Ruiz, G., et al. 2008. Atlas del clima marítimo. XXIII Congreso Latinoamericano de Hidráulica. Cartagena de Indias, Colombia, septiembre 2008, 15 pp (CD


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