Debris flow : mechanics, prediction and countermeasures

Preface Chapter 1 What is debris flow? Various sediment moving phenomena Definition of debris flow Classification and characteristics of debris flows Stony type debris flow Turbulent muddy type debris flow Viscous debris flow The significance of the mechanical classification of debris flows Classifications on the other points of view Chapter 2 Models for mechanics of flow 2.1 Models for solids and fluid mixture as the multi-phase flow 2.2 Single-phase continuum models 2.2.1 Visco-plastic fluid model 2.2.2 Dilatant fluid model 2.3 Two-phase continuum models (Mixture theory) 2.3.1 Stress equilibrium equations 2.3.2 Coulomb mixture theory (Quasi-static debris flows) 2.4 Theory for subaerial rapid granular flows 2.4.1 Particle collision stress 2.4.2 Kinetic stress 2.4.3 Skeletal stresses 2.4.4 Constitutive relations 2.4.5 Application of the theory to dry granular flow 2.4.6 Comparison with other constitutive relations for inertial range 2.5 Role of interstitial fluid in inertial debris flows 2.6 The mechanism of immature and turbulent muddy debris flows 2.6.1 Immature debris flow 2.6.2 Turbulent muddy debris flow 2.7 Generalized theory for inertial debris flows 2.7.1 Theoretical considerations 2.7.2 Verification by experimental data 2.7.3 Approximate solution for solids concentration and resistance to flow 2.8 Newtonian fluid model for viscous debris flow 2.8.1 Theoretical considerations 2.8.2 Verification by experiments Chapter 3 Initiation and development of debris flow Initiation and development of debris flow due to gully bed erosion The formation of incipient debris flow by the effects of surface water runoff The development of stony debris flow on sediment bed Verification of the theory by experiments Landslide-induced debris flow Model for the transformation into debris flow Mathematical model for the one-dimensional motion of an earth block Numerical simulation of earth block and debris flow motions across three-dimensional terrain Debris flow and flood flow induced by collapse of natural dam Formative conditions and shapes of natural dam Failure in entire channel width and the resulting debris flow Prediction of debris flow/flood flow induced by the overflow in partial width Chapter 4 Characteristics of fully developed flow Translation of debris flow surge and the shape of the snout The case of stony type debris flow The case of viscous type debris flow Boulder accumulation at the forefront of stony debris flow Various concepts for the mechanism The theory of Takahashi (1980) Competence to transport large boulders The cause of intermittency Debris flow around bend Routing of debris flow in the transferring reach Kinematic wave method Dynamic wave method Chapter 5 Processes and geomorphology of deposition One-dimensional stoppage/depositing processes of stony debris flow The arrival distance at the abrupt change in channel slope Topography of deposit formed at an abrupt slope change Numerical simulation of depositing process One-dimensional depositing process of turbulent muddy debris flow Formation of debris flow fan Description of the experimental results for stony debris flow and empirical presentations of the feature of debris flow fan Numerical simulation of fan formation process and its verification Numerical simulation of fan formation by turbulent debris flow Particle size distribution in the fan formed by stony debris flow General situations found in the field and experimental data Mathematical model for particle size distributions Erosion and deformation of debris flow fan Experiments for the process of erosion Model and its verification for the fan comprised of uniform material Model and its verification for the fan comprised of heterogeneous material Chapter 6 Debris flow disasters and their reproduction by computer simulations The rain storm disasters at Okuetsu Outline of the disaster The natural dam formation and the damages done by backwater Processes of destruction of the natural dam and damages downstream Horadani debris flow disasters Outline of the disaster Hydrograph estimation of the debris flow Reproduction of debris flow depositing area on the fan Collapse of the tailings dam at Stava, Northern Italy Outline of the disasters Reproduction of the debris flow in the Stava River and its verification Disasters caused by the eruption of Nevado del Ruiz Volcano Outline of the disasters Reproduction of the phenomena Sediment disasters in Venezuela Outline of the disasters Debris flow routing under an arbitrary rainfall condition Reproduction of debris flow hydrograph and others in the Camuri Grande River Reproduction of sediment flooding on the Camuri Grande fan Debris flow disasters at Atsumari, Hougawachi, Minamata City Outline of the disasters Reproduction of the processes of debris flow Chapter 7 Countermeasures for debris flow disasters Methods to prevent from debris flow generation Hillside works Drainage works Groundsill and bed girdle Debris flow control by closed type check dam Sediment depositing process behind check (sabo) dam Erosion process of the deposit behind sabo dam Effects of sediment control by sabo dam to downstream Debris flow control by open-type sabo dams Kinds and sediment checking mechanism of open-type sabo dams Blocking model of grid-type dam Model for debris flow controlling by grid-type dabo dam Determination of the optimum spacing and the optimum position to install Making debris flow harmless by channel works and training walls Design of countermeasures on the fan of the Camuri Grande River Management of debris flow by training dike Design debris flows for the countermeasure planning Method based on the previous data Prediction of total sediment runoff by field investigation Theoretical prediction of debris flow scale Debris flow prone ravines and hazardous area Debris flow prone ravine Hazardous zone by debris flow Prediction of debris flow occurrence by rainfall References Notations Index