Application Study On X-Shape Flaring Gate Pier For Kunlong Hydropower Station

Flood discharging energy dissipation has long been playing an important part in thehydraulic engineering development process. To some extent, it determines the layout of waterconservancy project. More importantly, it is one of the important guarantees for the safeoperation of the dam. Due to the unique characteristics of flow ternary hydraulic jump and thesignificant effect of energy dissipation, the form of energy dissipation which combines stillingfloor with flaring gate pier has been widely used in recent years. But in the running of theAnkang, Wuqiangxian and Jinghong hydropower station, the stilling basin slab of thecombined energy dissipation existed to varying degrees of instability. According to the survey,the nappe has a strong impact on the stilling basin base after entering the stilling basin. Theincreasing soleplate fluctuating pressure resulting in stilling floor anti-floating stability safetywhich is the main factor to induced accidents. Therefore, strengthening the study of hydrauliccharacteristics of the combined energy dissipation forms is very necessary and has significantimpact on the practical engineeringIn this paper, the author took Burma Danlun river Kunlong hydropower station flooddischarge buildings as research object, Kunming survey and Design Institute of ChinaHydropower Consulting Group provided the engineering dates, established hydraulic modelin water conservancy engineering hydraulic test hall. According to comprehensive summaryand analysis the basic materials such as the original design discharge capacitycharacteristics of the overflow surface, water tongue shape and stilling basin water flowcharacteristics, pressure characteristics and the characteristics of erosion and deposition of thedownstream, combined with the actual situation and specific requirements of this project,determined the modification scheme and the recommended scheme’s line and policy, proposedscheme to meet the requirements of the form of energy dissipation which combined theX-shape flaring gate pier and stilling basin.In the final scheme, the author conducted the thorough research to the hydrauliccharacteristics of combined energy dissipater: X-shape flaring gate pier and stilling basin. Byverifying the overflow orifice discharge capacity characteristics, find that the flaring gate pierhas a certain impact on the spillway discharge capacity, but the effect is slightly, the mostsignificant is only1.3%.It is Provide the basis for optimization of flood operationcombination. By observing the water tongue shape and stilling basin water flow characteristics of the combined energy dissipation, the author was aware of the dual hydraulicjump feature is obvious in low water level and when in the high water level, thecharacteristics of the ternary water jump increasing, the energy dissipation effect isremarkable, which provide a basis for the optimization of the energy dissipator shape andsection size. According to the measured velocity distribution of the flood discharge buildingand erosion and deposition of the downstream channel, statistic the depth of scour hole below440.0m and the sedimentation height on the apron above437.0m. Statistical results showedthat the maximum height of deposition appears when the crest outlet release the maximumflood waters flow in checking condition, sedimentation height is12.0m,4.0m lower than theend sill. It can determine the siltation will not enter the stilling basin, providing the basis foroptimize the riverbank protection engineering measures. By working with the characteristicsof fluctuating pressure in the form of energy dissipation which combines stilling floor withflaring gate pier, the study indicates that the shape of flaring gate pier, the length of stillingbasin, the height of end sill,△H andoperation mode are the main factors in influencingcharacteristics of fluctuating pressure. Then the paper summarizes the changing principle ofcharacteristics of the fluctuating pressure under the influence of various factors, and itprovides some references for the design of energy dissipation.The final scheme’s test results show that X-shape flaring gate pier and stilling basincombined energy dissipation meet the design requirements, successfully solved the BurmaDanlun river Kunlong hydropower station hydraulics engineering problems.