Experimental Study On The Design Of Spillway With High Water Head And Large Unit Discharge

Hydropower, as a clean and renewable resource, is seen to have a great future in the developing countries as the global energy has gone scarcer and the control standard for greenhouse gas release has become more rigorous. However, thanks to the advancement of dam design theory and ability, accompanied with the improvement of construction equipment and methods, many newly accomplished big scale structure for discharge purpose all possess common characters like "high head", "immense discharge" "narrow valley", which assign aration and dissipation to an outstanding position, in another word, erosion reduction by aration and energy dissipation are the keys and difficulties in projects nowadays.This paper, based on the previous study outcomes, primarily discusses the basic theory of aration and dissipation. The Bakun hydropower project in Malaysia is the case study in this paper for the project is characterized with mass unit discharge capacity, high velocity, and frequent usage, etc. Issues like discharge capacity, erosion reduction by aration, dissipation and side wall viberation are toughed in this paper on the ground of model test study, project analogy and computations, etc. As a result, the paper proposed the measures for spillway aration and dissipation which also meet the relavent standards and in principle resolved the issue of deficient discharge capacity rose from original design. The paper also justified the vibaration problems of high thin sidewall under the mass unit discharge and high velocity, analyzed the influence of certain flow velocity and flow regime in approach channel on discharge ability and the influence of flow regime in chute on the duration of the aration protection.Bakun project is located on the Balui river of Sarawak state of Malaysia. The average carryover discharge is 1314m~3/s. The average carryover rainfall reaches 4500mm. The dam is of a concrete face rockfill dam with the Max. dam height of 205m. The total reservoir capacity is 440×10~6 m~3. The total installed capacity is 8×300MW. The spillway, designed at the left bank, is the only structure for discharge. The Max. discharge capacity is 14600 m~3/s, the Max. unit discharge capacity is 292 m~3/s, and the Max. flow velocity in chute reaches 47 m/s Resolution of the issues like discharge capacity, erosion reduction by aration, dissipation, sidewall vibration can be of valuable reference to other similar proposed projects.