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砂防学会誌,Vol.55,No.3,p.33-42,2002
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石礫型及び乱流型土石流の一般理論とその実用化モデル
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Generalized theory of stony and turbulent muddy debris‐flow and its practical model
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論文
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高 橋 保* 里 深 好 文*
Tamotsu TAKAHASHI Yoshifumi SATOFUKA
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Abstract
Debris flows are classified inside the ternary phase diagram whose three apices represent the hundred percent of the total shearing stress within flow is shared by the stresses due to visco‐plasticity of the material, brief and enduring particle contact, and mixing of material, respectively. The inertial debris flow, a general term for stony, immature, hybrid and turbulent muddy debris flows, exists close to the opposite side of the apex representing the hundred percent share of the effect of visco‐plasticity. A generalized theory of inertial debris flow is developed imagining a hybrid debris flow whose lower part is the densely concentrated particle‐colliding layer and the upper part is particle suspension layer. The ratio of these two layers depends on the hydraulic conditions, and in stony debris flow the particle‐colliding layer prevails in the entire depth and in turbulent muddy flow the particle suspension layer occupies almost all the depth. The theory is based on the constitutive equations for an inertial granular flow and the turbulent suspension equation. The experimentally obtained characteristics, for example, the solids concentration in flow for a certain bed slope becomes large if comprising particle diameter becomes small, are well explained quantitatively. The theory is modified to give the solids concentration and the resistance to flow in the convenient forms easily applicable to the estimation of debris flow under actual conditions.
Key words:debris flow, stony debris flow, turbulent muddy debris flow, velocity, solids concentration
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砂防学会誌 Vol.55 No.3(242)September 2002
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