Study On Incipient Motion Of Gravel Sediment In The Deep Trough Of The Mountain River

The mountain river is common in the river, which water and sediment movement characteristics are complex. At present, plenty of research has been done on the mountain river, but there's few research on deep trough in Mountain River of the gravel sediment incipient motion. Therefore, to carry out the low on deep trough in mountain river of the gravel sediment incipient motion has important theoretical and practical value.This paper collects large volume of mountain river data in southwest china's, given the definition of the deep trough in the mountain river. By the author's definition, analysis the river terrain data information of the Yangtze River from Yibin to Yichang section, Found out the deep troughs are widespread phenomenon, then classified and analysis the deep trough, and preliminary study of its formation reason: Basic on specific geological structure and different lithology composition, caused by the power of water.Analysis the data of the deep trough in the mountain river found, the key factor affect the gravel sediment incipient motion is the negative slope and the widening in the export of the deep trough. Accordingly, analysis the theoretical of the gravel sediment incipient motion, deduced the theory formula in the deep trough of the mountain river.At the same time, design the trial model, through the enormous amount of test data, fitting out the laws of the gravel sediment incipient in the deep trough of the mountain river. When the negative slope from flat slope to angle of sand, the need flow velocity for sediment incipient motion is increase. When the negative slope from angle of sand to vertical, the need flow velocity for sediment incipient motion is unchanged. In the course of the trial, found gravel sediment in large nagtive slope circumstance has specialincipient mode------vertical spiral incipient. Under these circumstances, the sedimenttransport a great distance, through the complex terrain in the mountain river.Finally, take the different gravel sediment incipient motion situation to a unification formula, this formula fit the measured data very well, found the unification formula consider comprehensive and practical good.