Perbandingan Gerusan Lokal yang Terjadi di Sekitar Abutment Dinding Vertikal Tanpa Sayap dan dengan Sayap pada Saluran Lurus, Tikungan 90°, dan 180° (Kajian Laboratorium)

Agung Wiyono, Joko Nugroho, Widyaningtias Widyaningtias, Eka Risma Zaidun

Abstract


Abstrak. Fenomena kerusakan jembatan akibat gerusan pada pondasi pier atau abutment sulit diamati secara langsung. Salah satu metode untuk menyederhanakan adalah dengan pemodelan fisik di laboratorium. Tujuan penulisan jurnal ini adalah membandingkan gerusan yang terjadi di sekitar abutment dinding vertikal tanpa sayap dan dengan sayap pada saluran lurus, tikungan 90o, dan 180o. Perbandingan difokuskan pada gerusan lokal jenis live -bed scour dan terjadinya transportasi sedimen sepanjang pengaliran debit 4, 5, 6, dan 7 liter/detik pada model saluran. Penelitian dilakukan dengan membangun model saluran terbuka dengan dinding fiberglass dan dasar saluran terbuat dari semen, saluran memiliki bagian lurus serta sudut tikungan 90° dan 180°. Hasil parameter fisik berupa kecepatan dan kedalaman gerusan, dibandingkan secara analitik dengan menggunakan Formula Laursen (1960), Froehlich (1989), dan Mellvile (1997). Hasil perbandingan menunjukkan bahwa pada abutment
dinding vertikal tanpa sayap, hasil perhitungan Formula Laursen paling mendekati hasil pengamatan dengan persentase kesalahan 20,02%. Sedangkan untuk abutment dinding vertikal dengan sayap, persentase kesalahan terkecil sebesar 28,17%, dengan menggunakan Formula Froehlich (1989). Untuk abutment dinding vertikal tanpa sayap, kedalaman gerusan maksimum terjadi di sekitar hulu abutment, dan segmen tengah abutment untuk abutment dinding vertikal dengan sayap. Untuk kedua tipe abutment sedimentasi tertinggi terjadi di sebelah hilir.

Abstract. The damage phenomenon of the bridge due to scour on pier foundation or abutment is difficult to observe directly. One of the methods to simplify this phenomenon is modeling in the laboratory. The purpose of this research is to compare scouring around vertical wall and vertical wing-wall abutment in straight channel, 90o, and 180o curve channel. Scouring comparison focused on the live-bed scour and the occurrence of sediment transport along the 4, 5, 6, and 7 liters / second discharge on the channel model. Results of physical parameters such as velocity and depth of scouring compared with the analytical using Laursen (1960), Froehlich (1989), and Mellvile (1997) formula. The result from each calculation will be compared with the observation data. The result
shows that maximum scouring for vertical wall and vertical wing-wall abutment occurred in upstream and middle of abutment respectively. Furthermore, sedimentation for both of types is around downstream of abutment. From the analytical comparison, Laursen’s Formula gives closer accuracy for vertical wall abutment than others formulas, with the percentage of error is about 20,02%. While, Froehlich’s Formula gives 28,17% for wing-wall abutment.

Keywords


Abutment; Gerusan; Saluran menikung; Saluran lurus; dan Sedimentasi

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References


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