| With the increase of building dams, the relative key techniques of scouring at the down reach of dams need to be studied imminently. If the forecast results of the maximum depth of scouring is more accurate. It is possible to possible to service engineering construction and national economic with higher quality. There are several factors affected to various conditions. The estimation formula was built with fewer parameters. At present, there are many research methods that is far from satisfied to engineering application and has not formed united knowledge on theory. So, this study has realistic meaning and theoretical significance.On basis of analyzing the domestic and international documents, The author of this paper researches the relative key techniques of scouring at the down reach of dams through flume experiment combing theory analysis. The work and main conclusion of this paper are as follows:(1) Based on collection and analysis of related literatures, it was summarized that the relative theory and calculation method of scouring at the down reach of dams.(2) To make a conclusion by the analysis of literatures at home and abroad, it was summarized that adjustment of riverbed(including the adjustment of longitudinal section , river width, bed silt composition and the limited scour depth) and the falling of water level in lower reaches of some internal and external hydro-junction. And the relation between adjustment of riverbed and the falling of water level was analyzed.(3) On the basis of this mould test,much of data is obtained. This paper compare some different effected conditions of clear water scouring,and quantitative analyze its rule by these test data.(4) it was observed and studied that the longitudinal deformation of riverbed. The estimated formulas for bed load discharge changed with the duration of scouring.(5) Based on conservation principle of sediment amount, the estimated formulas was established with the scouring depth of riverbed. The formulas involve suspended load and bed load. The computed results were in better agreement with the experimental ones.(6) Based on flume experiment, it was discovered that the armor layer had three species of kinds. Based on conservation principle of sediment amount, grading formula of armor layer was deduced in the theory and was validated.At last, the author of this paper points out some problems to be solved in the future and suggestions of improvement of the model test. |
