ESTIMATING CRITICAL SHEAR VELOCITY OF INCIPIENT COHESIVE SEDIMENT MOTION OF SHALLOW SLOPE UNDER SURFACE RUNOFF

摘要

Surface runoff is an important factor inducing soil erosion of shallow slope. Due to the complexity of material composition, grain arrangement and porosity structure, however, it is difficult to directly give the critical shear velocity of incipient motion under surface runoff if all matters of cohesive sediment are taken into account. Considering the bonding effect of cohesive sediment, a closed-form solution for critical shear velocity is presented in this work Three primary assumptions, i.e., slope angle less than 30 deg, laminar for surface runoff and uniform film water around soil particles, are made in deriving the solution. The bonding force of cohesive sediment stemming from film water contact can be embedded in the force analysis of single particle. Laboratory scouring test results validate the present solution.