エネルギー散逸機構に基づく流砂モデル

Abstract

The present study emphasizes that no differences exist in the dynamics of grainmovement in debris flow and general bed-loads, so far as bed shear stress is keptgreater enough for active movement of sediment.The structure of shear stress in the sediment layer under consideration isdiscussed in terms of a theory of debris flows which has been developed by theauthors. This brings about the differential equations for velocity and particleconcentration in the moving layer of sediment. These equations are solvedanalytically, assuming a linear profile of sediment concentration, and also analysednumerically. No significant differences are found between the results obtained bythe two; the approximate solution and the numerical solution.A bed load equation, which should be called a "sediment load formula", isdeveloped by using the formulas for the velocity profile of sediment layer and theflow depth of sediment layer. According to the formula, non-dimensional bed loadrate is proportional to r*5/2 (r* is the non-dimensional shear stress). This equation isverified in terms of flume data.