Levee foundation piping is a complex and dynamic process.For the levee foundation with a thin layer of relatively impermeable clay over the permeable sand bed,a finite element model is presented to simulate the source tracing development of internal soil piping.In eiew of the influence of sand concentration on the flow resistance,the coefficient of the equivalent permeability of the pipe flow is given according to the form of Darcy formula.Thus the simulation of both piping zone and the normal soil zone is unified to the conventional seepage analysis method.The relationship of soil erosion rate of the pipe wall and the shear stress of the flow is introduced into the balance equation of sediment transportation to simulate the dynamic development of the piping channel.The dynamic development of the piping channel with time is obtained by the solution of the seepage equation and the sediment transport equation.The simulation of a sand tank test on piping shows that,the model can quantitatively simulate the dynamic development of piping with time.
; 邓琴芳
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