Studi Perencanaan Tembok Laut (Seawall) di Pantai Bobolio Kabupaten Konawe Kepulauan Provinsi Sulawesi Tenggara

Aji Prakoso Nimanto, Heri Suprijanto, Andre Primantyo Hendrawan

Abstract


ABSTRAK: Pantai Bobolio mengalami perubahan morfologi pantai akibat erosi yang terjadi dari besarnya terjangan gelombang laut sehingga mengakibatkan kemunduran garis pantai. Kerusakan pemukiman penduduk, fasilitas umum serta bengunan lainnya yang disebabkan oleh kemunduran garis pantai dapat diminimalkan degan membangun tembok laut. Perencanaan tembok laut mula-mula dilakukan dengan menganalisis gelombang datang dengan kala ulang 25 tahun yang bertujuan untuk memperoleh dimensi tembok laut. Setelah didapatkan dimensi, akan dihitung stabilitas bangunan terhadap kelongsoran rotasi dan daya dukung tanah. Pondasi tiang pancang yang direncanakan mengunakan 3 alternatif berupa kayu bakau, kayu gelam dan bambu. Hasil perencanaan ini diperoleh gelombang dominan dari arah Tenggara dengan tinggi gelombang signifikan sebesar 1,50 m untuk kala ulang 25 tahun. Tembok laut terletak pada elevasi 0,0 m dengan tinggi puncak pada elevasi + 5,10 m, panjang 1315 m sepanjang garis pantai, berat batu pelindung terluar sebesar 2,11 ton dengan diameter 1,16 m. Analisis stabilitas lereng terhadap kelongsoran rotasi mengunakan bantuan software Geostudio Geoslope dengan metode Fellenius, Bishop dan Janbu dapat dikatakan aman. Pondasi tiang pancang direncanakan sedalam 20 m dengan diameter tiang pancang sebesar 0.2 m. Total rencana angaran biaya (RAB) alternatif I dengan material pondasi tiang pancang menggunakan dolken kayu bakau sebesar Rp 62.448.965.000,00, alternatif II dengan material pondasi tiang pancang mengunakan dolken kayu gelam sebesar Rp 60.381.849.000,00 dan alternatif III dimana material pondasi tiang pancang mengunakan cerucuk bambu sebesar Rp 63.381.400.000,00.

Kata kunci: tembok laut, kelongsoran rotasi, geostudio geoslope, pondasi tiang

 

ABSTRACT: The coastal morphology of Bobolio Beach has been changed due to erosion from wave movement.The damages of the settlements, public facilities and other buildings caused by the changes of coastline can be minimized by a seawall construction. The designing of seawall was first performed by analyzing the coming wave with a 25-year of return period to obtain the dimension. After the dimension is obtained, the stability of structure against the rotational slide and the bearing capacity of the soil can be evaluated. Three alternatives of pile foundation materials were used: mangrove wood, gelam wood and bamboo. From this study, it is observed that the dominant waves came from southeast with a significant wave height of 1.50 m for a 25-year of return period. As a final design, the height of seawall is 5.10 m with a length of 1315 m along the coastline. The weight of the outer protective rock is 2.11 tonnes with a diameter of 1.16 m. From the analysis of slope stability using Geostudio Geoslope software with Fellenius, Bishop and Janbu method indicates that this structure was safe against rotational slide. The depth of pile foundation is 20 m with a diameter of 0.2 m. The estimation of total cost with pile foundation using mangrove wood (alternative I) is Rp 62.448.965.000. As for alternative II using gelam wood and alternative III which bamboo piles was used, the estimations of total cost were calculated as Rp 60.381.849.000 and Rp 63,381,400,000, respectively.

Keyword: seawall, rotational slide, geostudio geoslope, pile foundation

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