火砕流の流動機構に関する研究

Abstract

A Merapi type pyroclastic flow is modeled in a laboratory flume in which the degassing takes place from the pyroclastic material itself.Fluidization of the bed due to the upward movement of the gass is the main cause of generation of the flow and the multi-layered structure of the flow; I.e., from the bottom to the upward direction the non-fluidized part, the fluidized laminar flow part, the turbulent strongly mixing part and the turbulent dispersion part, is observed in the experiments.The theory for the prediction of the thickness, velocity and the particle concentration of each layer is presented.The degassing rate from the pyroclastic material and the viscosity of the fluidized bed are the most important parameters to be determined by the further works which control the occurrence, flowage and deposition of the pyrocalstic flow.