INTERNAL EROSION OF EXISTING DAMS, LEVEES AND DIKES, AND THEIR FOUNDATIONS / L’ÉROSION INTERNE DANS LES BARRAGES ET DIGUES EN EXPLOITATION ET LEUR FONDATION

The Commission Internationale des Grands Barrages (CIGB) / International Commission on Large Dams (ICOLD) is a non-governmental International Organization which provides a forum for the exchange of knowledge and experience in dam engineering.The Organization leads the profession in ensuring that dams are built safely, efficiently, economically, and without detrimental effects on the environment. Its original aim was to encourage advances in the planning, design, construction, operation, and maintenance of large dams and their associated civil works, by collecting and disseminating relevant information and by studying related technical questions.Since the late sixties, focus was put on subjects of current concern such as dam safety, monitoring of performance, reanalysis of older dams and spillways, effects of ageing and environmental impact. More recently, new subjects include cost studies at the planning and construction stages, harnessing international rivers, information for the public at large, and financing.

• TABLE DES MATIÉRESTABLEAUX & FIGURESPRÉFACE ET REMERCIEMENTS RÉSUMÉ 1. GÉNÉRALITÉS1.1 CE QUE DIT LE VOLUME 1 SUR L’ÉROSION INTERNE1.2 PROCESSUS D’ÉROSION INTERNE 1.3 NEUF POINTS FUNDAMENTAUX DE L’ÉROSION INTERNE1.4 JUSTIFICATION DES NEUFS POINTS FONDAMENTAUX DE L’ÉROSION INTERNE1.5 UTILISER LA COMPRÉHENSION RÉCENTE DES MÉCANISMES D’ÉROSION2. ÉTUDES DE CAS2.1 LEÇONS APPRISES DES RUPTURES ET INCIDENTS2.2 RUPTURES ET INCIDENTS DUS À L’ÉROSION DE CONDUIT2.3 RUPTURES ET INCIDENTS DUS À L’ÉROSION RÉGRESSIVE LOCALE ET GLOBALE2.4 RUPTURES ET INCIDENTS D’EROSION DE CONTACT2.5 RUPTURES ET INCIDENTS DE SUFFUSION2.6. RUPTURES ÉVITÉES PAR DES FILTRES À ÉROSION LIMITÉE OU IMPORTANTE ET AUTRES MATÉRIAUX DE REMBLAI3. RECONNAISSANCES3.1 PRINCIPES D’INVESTIGATION DE L’ÉROSION INTERNE3.2 CAROTTAGES POUR ÉCHANTILLONS INTACTS SOUS LA NAPPE3.3 DETECTION DES FUITES: MÉTHODES DIRECTES3.4 DETECTION DES FUITES: MÉTHODES GÉOPHYSIQUES 4. ESSAIS DE LABORATOIRE4.1 INTRODUCTION4.2 ÉROSION DE CONDUIT: MESURES DE LA CONTRAINTE CRITIQUE (TC) ET DU COÉFFICIENT D’ÉROSION (CE)4.3 ESSAIS DE SUFFUSION4.4 ESSAI D’ÉROSION DE CONTACT4.5 ESSAIS DE PERMÉABILITÉ, ÉRODABILITÉ ET CAPACITÉ FILTRANTE DES REMBLAIS ET DES FILTRES5. RÉHABILITATION5.1 INTRODUCTION5.2 RÉPARATION DE L’ÉROSION DE CONDUIT5.3 RÉPARATION DE L’ÉROSION RÉGRESSIVE5.4 RÉPARATION EN CAS D’ÉROSION DE CONTACT5.5 RÉPARATION EN CAS DE SUFFUSION6. SURVEILLANCE 6.1 OBJECTIFS ET PRINCIPES DE LA SURVEILLANCE DÉDIÉE A L’ÉROSION INTERNE6.2 SURVEILLANCE ET AUSCULATION À LONG TERM6.3 PIÉZOMÈTRES, PRESSIONS ET GRADIENTS HYDRAULIQUES6.4 DÉTECTION DES FUITES7. REFERENCESTABLE OF CONTENTSTABLES & FIGURESFOREWORD AND ACKNOWLEDGEMENTS EXECUTIVE SUMMARY1. OVERVIEW 1.1 WHAT VOLUME 1 (ICOLD, 2017) TELLS US ABOUT INTERNAL EROSION1.2 INTERNAL EROSION PROCESSES1.3 NINE FUNDAMENTAL POINTS ABOUT INTERNAL EROSION1.4 JUSTIFICATION OF THE NINE FUNDAMENTAL POINTS1.5 USING THE NEW UNDERSTANDING OF INTERNAL EROSION MECHANICS2. CASE HISTORIES2.1 LESSONS FROM FAILURES AND INCIDENTS2.2 FAILURES AND INCIDENTS FROM CONCENTRATED LEAK EROSION2.3. FAILURES AND INCIDENTS FROM BACKWARD EROSION AND GLOBAL BACKWARD EROSION2.5. FAILURES AND INCIDENTS FROM SUFFUSION2.6. FAILURE PREVENTED BY ‘SOME-’ AND ‘EXCESSIVE-’ EROSION FILTER AND FILL MATERIALS IN EXISTING DAMS3. INVESTIGATIONS3.1 FUNDAMENTALS OF INTERNAL EROSION INVESTIGATIONS 3.2 DRILLING FOR COMPLETE GRANULAR SAMPLES BELOW WATER TABLE3.3 LEAKAGE DETECTION: DIRECT METHOD3.4 LEAKAGE DETECTION: GEOPHYSICAL METHODS3.5 IN-SITU PERMEABILITY AND VELOCITY4. LABORATORY TESTS4.1 INTRODUCTION4.2 CONCENTRATED LEAK EROSION: TESTS TO DETERMINE CRITICAL SHEAR STRESS (TC) AND COEFFICIENT OF EROSION (CE)4.3 SUFFUSION TESTS4.4 CONTACT EROSION TESTS4.5 TESTS ON PERMEABILITY, ERODIBILITY AND FILTERING CAPABILITY OF FILLS AND FILTERS4.6 CRACK EROSION TEST (CRET)5. REMEDIATION5.1 INTRODUCTION5.2 REMEDIATION TO RESIST CONCENTRATED LEAK EROSION5.3 REMEDIATION TO RESIST BACKWARD EROSION5.4 REMEDIATION TO RESIST CONTACT EROSION5.5 REMEDIATION TO RESIST SUFFUSION6. SURVEILLANCE 6.1 SURVEILLANCE IN RELATION TO INTERNAL EROSION6.2 LONG-TERM SURVEILLANCE AND MONITORING6.3 PIEZOMETERS, PORE PRESSURES AND HYDRAULIC GRADIENTS6.4 LEAKAGE DETECTION7. REFERENCES