Until now, the pore water pressure, which is one of the stress constituents
governing the flow characteristics of a steady, laminar debris flow, has b
een considered to be hydrostatic. We succeeded in measuring the pore water
pressure distribution in solid-water phase flows with a rolling mill. The e
xperimental results show that the pore water pressure actually exceeds the
hydrostatic pressure, and indicates that the excess pore water pressure ari
ses as a consequence of Reynolds stresses due to the shearing of interstiti
al water. (C) 2000 Elsevier Science Ltd. All rights reserved.