| Abstract | A new type artificial reef submerged breakwater, Seadome has multi functions which are coastal protection, marine habitat and recreation. Seadome has been constructed three locations, Phetchaburi, Pattani and Phuket with a main function for protecting coastal area from erosion. Monitoring of Seadome was conducted at Phetchaburi after one year of construction. Phetchaburi Seadomes have been relocated to deeper water zone after the identification of the failures. Seadome design was based on empirical approach and did not include possible failure modes that have occurred for conventional breakwaters. Moreover, scour was suspected to be the main cause of Seadome failure. Therefore, the analysis of failures needs to be systematically determined. The main purposes of this study are to analyze the Seadome stability and develop a framework for analysis and then develop to be a design framework of Seadome.
The stability of Seadome was analyzed based on solitary breaking wave conditions. The stability of Seadome was categorized into two types which are a single and a combined force to failure analysis. Undertow force is a new contribution of this study including into the stability analysis. The single analysis was analyzed under 7 failure modes, overturning, sliding, bearing capacity, settlement, scour and liquefaction. Analysis of submerged breakwater as a group and undertow scour are a new contribution in this study. The results from analysis of bearing capacity, settlement, undertow scour, scour from non-breaking wave and liquefaction from standing waves show that these failure modes will not have significant impacts on Seadome stability. Overturning of large Seadome for single unit and group unit on sand will make a failure occur. For the sliding, all single unit, medium Seadome group on sand and large Seadome group on both sand and geotextile can be moved as the breaking waves exerting. Scour induced from breaking waves and undertow is one of the main causes which can make Seadome inclined and tilted. Seadome can be burden into the ground by liquefaction from rocking of Seadome, however; this failure mode should be studied further as the lack of experiment data to calibrate and to explain the analysis results. Furthermore, the combined force to failure analysis have two cases which are undertow force and overturning, and undertow force and scour. This analysis is the new concept contributed in the present study. The results show that stability from combination of undertow force to overturning and scour is the same as single failure mode analysis.
Finally, the frameworks for analysis and design of Seadome were developed using the analysis results and verified with both before and after relocation of Seadome at Phetchaburi. This is a new contribution of the present study by developing a framework for proposing a systematic approach to determine Seadome stability instead of empirical approach which has been used for most of coastal structures.
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