Pengaruh Tirai pada kedalaman gerusan di sekitar abutmen

OELVA, Maria, Dr.Ir. Bambang Agus Kironoto

2005 | Tesis | S2 Teknik Sipil

di sekitar abutmen maupun karena degradasi dasar sungai. Penelitian ini bertujuan untuk mengetahui pengaruh pemakaian groundsill untuk menjaga agar dasar saluran tidak turun dan untuk mengetahui pengaruh pemakaian tirai dalam mereduksi kedalaman gerusan di sekitar abutmen. Penelitian ini dilakukan di laboratorium pada kondisi live-bed, dengan debit (Q) 3,21 liter/detik, kedalaman aliran (Do) 0,07 m, serta kemiringan saluran (So) 0,0004. Abutmen yang dipakai tipe wing-wall dengan sudut 450, dimensi panjang sisi belakang (L) 0,15 m dan panjang sisi depan (L) 0,08 m, lebar melintang (LA) 0,0375 m dan tinggi 0,30 m. Upaya pengendalian gerusan yang dipakai adalah tirai tiang zigzag dua memanjang, dengan variabel yang ditinjau adalah jarak antar as tiang tirai (S) 0,2LA dan 0,4LA, penempatan tirai dari abutmen (X) 3LA, 4LA, 5LA dan 6LA dan tinggi tirai (H) 0,2Do, 0,6Do, 0,8Do dan 1,5Do . Untuk menjaga agar dasar saluran tidak turun dipasang groundsill pada jarak 60 cm di hilir abutmen. Hasil penelitian menunjukkan bahwa pemasangan groundsill dapat mengurangi degradasi dasar saluran sebesar 14%. Jarak antar as tiang tirai terbaik adalah 0,2LA dan tinggi tirai terbaik adalah 0,8Do.

Bridge abutment was threatened by local scour around the abutment or by degradation of river bed. This research aimed to know the influence of the usage of groundsill to protect the base of the river from degradation and to know the influence of the usage of screen in reducing the depth of the scour around the abutment. This research was held in laboratorium by using experimental model. There are some conditions used in this model, they are live-bed condition, the flow rate (Q) was 3.21 l/s, the depth of the flow (Do) was 0.07 m, the bottom of the channel (So) was 0.0004. The abutment used was wing wall type with the angle 45o, the length of the back side (L) was 0.15 m while the front side (L) was 0,08 m, the cross width of the structure (LA) was 0.0375 m and the height was 0.3 m. The efforts carried out to control the scour was the usage of two zigzag pile screen paralel with the channel. The variabel concerned was the distance between axis to axis (S) 0.2LA and 0.4LA. The Placement of the abutment screen (X) was 3LA, 4LA, 5LA and 6LA and the height of screen (H) 0.2Do, 0.6Do, 0.8Do and 1.5Do. Groundsill was placed on 60 cm downstream of the abutment. The results of the research showed that the placement of groundsill could reduce the bed degradation to 14%. The best distance between the axis of pile screen was 0.2LA and the best height of screen was 0.8Do.

Kata Kunci : Bangunan Sungai,Abutmen,Gerusan Lokal,Tirai, local scour, live-bed scour, abutment