THE SPHERE DRAG RHEOMETER: A NEW INSTRUMENT FOR ANALYSING MUD AND DEBRIS FLOW MATERIALS

Abstract

The present study focused on novel rheometrical tool for the determination of the rheological
behavior of large particle mixtures with particular interest in the application to granular materials involving
in fast landslides as mud and debris flows. The main goal is the development of the Sphere Drag Rheometer
(SDR), a home-made large-scale rheometer that allow to estimate the rheological properties of these mixtures
considering particles up to 50 mm grain size. The SDR is composed of a sphere rigidly joined to a support
that moves at constant velocity into the mixture. Compared to standard rheometer, the SDR uses much higher
volume of mixtures of wider grain size distribution next to that in situ. Several pyroclastic soils collected
from the source area of debris flows occurred in Campania region (Southern Italy) were analyzed. The paper
reports the experimental results on fine particles mixtures, large particle mixtures, and their comparison. The
experimental results on fine mixture are compared with those obtained by conventional rheometrical tools
reported in previous papers.