Mechanical Characteristics of Debris Flow

A mechanism of occurrence of bore-like debris flow due to the appearance of overland flow on the debris accumulation is considered using the applying shear stress and resisting stress relationship in the bed. The criteria for the occurence of the nonstationary bed flow and the partly stationary bed flow are made clear. The partly stationary bed flow approaches a quasi-steady state, whose depth, velocity and concentration are predictive applying the concept of dilatant fluid introduced by Bagnold. Although the front height of the nonstationary bed flow increases versus distance, the translation velocity and concentration are nearly constant and flow characteristics are theoretically predictive by some appropriate assumptions.