INTERPARTICLE STRESSES AND CHARACTERISTICS OF DEBRIS FLOW.

Particle-to-particle interactions in a solid-liquid shear flow at high concentration are investigated experimentally in detail, in order to obtain information that could guide the formulation of the constitutive equations. Most of the grains in the flow collide at the 'upstream' quadrant on the surface of the relatively lower grains, and then override them until the grains separate at the 'downstream' quadrant. The interparticle stresses are conventiently divided into collision stress and contact stress. The former is evaluated theoretically by estimating the momentum transfer in many-body collisions, starting from the analysis of binary collisions. On the other hand, the latter is considered to be isotropic pressure expressed by the grain concentration and be related to the excess immersed weight of grains which can not be supported by the collision normal stress.