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標題: 變量流作用下之固床工沖刷室內試驗研究
Laboratory investigation of scour downstream of a grade-control structure under unsteady flows
作者: 張凱博
Chang, Kai-Po
關鍵字: grade-control structure;固床工下游;scour;unsteady flow;沖刷坑形態;沖刷深度;變量流
出版社: 土木工程學系所
引用: 1.何淑君(2009),「透水框架群應用於固床工下游沖刷保護之研究」,碩士論文,國立中興大學土木工程研究所。 2.彭明正(2008),「變量流作用下非均勻橋墩之局部沖刷量測與模擬」,碩士論文,國立中興大學土木工程研究所。 3.彭思顯(1994),「投潭水作用下局部沖刷之動態研究」,碩士論文,國立中興大學土木工程研究所。 4.盧昭堯、賴進松及林詠彬(2008),「河道固床工破壞機制與減沖促淤新工法研擬」,經濟部水利署水利規劃試驗所委託研究計畫成果報告。 5.Bormann, N. E. and Julien, P. Y., (1991) "Scour Downstream of Grade-Control Structures" J. Hydraul. Engrg., vol.117(5), 579-594. 6.Blinco, P. H. and Partheniades, E. (1971). “Turbulence characteristics in free surface flows over smooth and rough boundaries,” J. Hydraul. Res. IAHR 9, 43-69. 7.Briaud, J. L., Chen, H. C., Kwak, K. W., Han, S.-W., and Ting, F. C. K. (2001). “Multiflood and multilayer method for scour rate prediction at bridge piers.” J. Geotech. Geoenviron. Eng., 127_2_, 114–125. 8.Breusers, H. N. C., (1966). “Conformity and time scale in two-dimensional local scour,” Proc. Symposium on model and prototype conformity: 1-8, Hydraulic research Laboratory Poona (also Delft Hydraulic, Delft, Publication 40). 9.Breusers, H. N. C. and Raukivi, A. J., (1991) "Scouring" A.A. Balkema, 123-142. 10.Chang, W. Y., Lai, J. S. and Yen, C. L. (2004). “Evolution of scour depth at circular bridge piers.” J. Hydraul. Eng., 130(9), 905-913. 11.Dey, S. and Sarkar, A., (2006) "Scour downstream of an apron due to submerged horizontal jets" Journal of Hydraulic Engineering, ASCE, vol.132(3), 246-257. 12.Farhoudi, J. and Smith, K. V. H. (1982). “Time scale for scour downstream of hydraulic jump, Proceedings ASCE, 108(HY10), 1147-1161. 13.Farhoudi, J. and Smith, K. V. H., (1985). "Local Scour Profiles Downstream of Hydraulic Jump" J. Hydraul. Res., 23(4), 343-358. 14.Gaudio, R., Marion, A., and Bovolin, V. (2000). "Morphological effects of bed sills in degrading rivers" J. Hydraul. Res., 38(2), 89-96. 15.Gaudio, R. and Marion, A. (2003). “Time evolution of scouring downstream of bed sills,” J. Hydraul. Res., 41(3), 271-284. 16.Hoffmans, G. J. C. M., (1990). “Concentration and flow velocity measurements in a local scour hole, Report 4-90, Faculty of civil Engineering, Hydraulic and Geotecnical Engineering Division, Delft Univercity of Technology, Delft. 17.Hoffmans, G. J. C. M., anf Verheji, H. J. (1997). “Scouring manual,” Balkema, Rotterdam, The Nethelands. 18.Laufer, J. (1951). “Investigation of turbulent flow in a two-dimensional channel,” NASA Report 1053, NACA Technical note 2123, 37(2), 1247-1266. 19.Lenzi, M. A., Marion, A., Comiti, F., and Gaudio, R. (2002). “Local scouring in low and high gradient streams at bed sills,” J. Hydraul. Res., 40(6), 731-739. 20.Meftah, M. B. and Mossa, M. M. (2006). “Scour holes downstream of bed sills in low-gradient channels,” J. Hydraul. Res., 44(4), 497-509. 21.Nezu, I. (1977). “Turbulence intensities in open-channel flow,” Proc. Japan Soc. Civil Engrg. 261, 67-76 (in Japanese). 22.Oliveto, G., and Hager, W. (2005). “Further results to time-dependent local scour at bridge elements.” J. Hydraul. Eng., 131(2), 97-105. 23.Pagliara, S., (2007) "Influence of sediment gradation on scour downstream of block ramps" J. Hydraul. Eng., 133(11), 1241-1248. 24.Sumer, B. M., Christiansen, N., and FredsØe, J. (1993). “Influence od cross section on wave scour around piles,” J. Waterw., port, Costal, Ocean Eng., 119(5), 477-495. 25.Tregnaghi, M., Marion, A., and Coleman, S. (2009). “Scouring at bed sills as a response to flush flodds,” J. Hydraul. Eng., 135(6), 466-475.

River bed elevations of many rivers in the west of Taiwan have lowered down seriously. River and bridge management bureaus often construct grade-control structures to stabilize the riverbeds and reduce the scouring of the pier foundations.

The aim of this research is to investigate the edge failures downstream of the grade-control structures. A series of experiments were conducted under the clear-water conditions with sand and gravel, two riverbed slopes, two ramp slopes for the grade-control structures, and two flow discharges. Furthermore, unsteady flow experiments with different types of hydrograph consisting of four unit discharges were performed. The shapes of the scour holes were discussed and the evolution of the scouring process for unsteady flows were simulated.

In regard to the results of the steady flow experiments, empirical formulas were developed to describe the equilibrium scour hole and the time variations of the scour depth. In general, the maximum scour depth and its location, the length of the scour hole, and the flow depth at the last step of the grade-control structure increase with an increase of the channel bed slope, densimetric Froude number, tail water depth and critical depth.

As for the results of the unsteady flow experiments, a concept of superposition is used to estimate the variations of the scour depth for four different types of hydrograph based on the measured scour data for the steady flows, and generally the results were consistent with the measured values for the unsteady flows. In addition, the evolution of the scour depth for an unsteady flow was also simulated by the superposition concept using the simulated scour evolution curves for the steady flows. Similarly, reasonably good results were obtained as compared with the measured scour evolution curve for the unsteady flow.
其他識別: U0005-1008201013092400
Appears in Collections:土木工程學系所

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