Erosion and Deposition Characteristics of Sediment in Pressure Pipe
In order to clarify the movement characteristics and critical non-depositing velocity of sediment in pressure pipe under complex topographic conditions,the velocity of different grain sizes of sediment under different motion states was investigated by model test.The effects of different sediment grain sizes,sand volume and sediment grade on the criti-cal non-silt flow rate were analyzed.Meanwhile,discontinuous movement as bedload,sediment with particle size between(0.075-0.600)mm moves in multiple elliptical shapes in the rising and horizontal sections of the pipe,steeper descents are banded.Sediment with particle size between(0.600-1.250)mm moves in the form of a hill in the pipe.The critical velocity of water in the state of sediment movement tends to increase with the increase of sediment grain size,and contin-uous movement as bedload is the best sediment conveying state.The critical non-depositing velocity all increase with in-crease of sediment grain size,sand volume,and sediment grading.The sediment grain size is the main factor influencing the critical non-depositing velocity,and the amount of sand and sediment gradation are secondary factors that affect the critical non-depositing flow rate.The results can provide reference for the design and application of the pressure pipe in water diversion engineering in complex topographic conditions.
pressure pipesediment movement patternflow rate definition of sediment movement statecritical non-depositing velocity
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