Uji Model Hidraulik Intake dan Sandtrap Bendung Sei Silau Kabupaten Asahan

NOVITASARI A, Dr Istiarto, ST., M.Eng.

2015 | Skripsi | S1 TEKNIK SIPIL

Bendung Sei Silau di Kabupaten Asahan dibangun untuk menambah suplai air ke daerah irigasi dengan luas lahan 6000 ha. Diperlukan studi model fisik hidraulik 3D untuk memastikan bahwa desain bangunan mampu beroperasi sesuai rencana. Model dibuat dengan skala 1:30 tanpa distorsi. Beberapa aspek yang diamati adalah debit yang masuk ke saluran intake dan efisiensi pembilasan pada sandtrap. Pada penelitian ini juga dilakukan modifikasi bangunan dengan menambah sayap pengarah aliran di depan pintu intake dengan dimensi 13,8 m x 2,7 m x 1,4 m. Berdasarkan hasil uji model fisik, debit intake dengan kondisi bangunan dan skenario bukaan pintu sesuai desain rencana adalah 6,68 m3/s. Penambahan sayap pengarah aliran mampu menaikkan debit intake sebesar 8%. Kecepatan pembilasan pada saat pengujian hanya sebesar 45% dari debit rencana mengakibatkan kurang efektifnya pembilasan. Pada saat pembilasan, sedimen paling banyak terbilas adalah pada bukaan pintu satu (P1) dibuka yaitu sebesar 24%.

Sei Silau Dam in Asahan District was designed to enhance the water supply of irrigation for six thousand hectares because Sei Bunut which is the main source of water supply can not fulfilled the needs of irrigation. Hydraulic three dimension model study is required to assure that the building design is capable to operate as it planned for. The purpose of this research is to test the performance of intake and sandtrap of Sei Silau Dam when operating. The model was built undistort with scale of 1:30. Some aspects that observed was the inlet discharge of intake and the flushing efficiency of sandtrap. Modification is conducted by adding the guide wall in front of intake's door with dimension 13,8 m x 2,7 m x 1,4 m. The calculation of discharge is analyze by measuration on site with various intake gate openings and interpolation of guide wall's changes, while flushing efficiency by measuring the flushed area. Base on the hydraulic model's results, intake's discharge by the planned condition is 6,68 m3/s. Meanwhile the guide wall can increase 8% of intake discharge. The flushing on sandtrap-test show the velocity of the flushing is only 45% from the velocity that have planneed. When flushing is running, the most sediment that flushed away by the scenario of north intake opened and the south one's closed is 24%.

Kata Kunci : kinerja, debit, sedimen