Author Biographies 1 Introduction 1.1 Outline of the book 1.2 Types of embankment dams and their main features 1.3 Types of concrete dams and their main features 2 Key geological issues 2.1 Basic definitions 2.2 Types of anisotropic fabrics 2.3 Defects in rock masses 2.3.1 Joints 2.3.2 Sheared and crushed zones (faults) 2.3.3 Soil infill seams (or just infill seams) 2.3.4 Extremely weathered (or altered) seams 2.3.5 The importance of using the above terms to describe defects in rock 2.4 Defects in soil masses 2.5 Stresses in rock masses 2.5.1 Probable source of high horizontal stresses 2.5.2 Stress relief effects in natural rock exposures 2.5.3 Effects in claystones and shales 2.5.4 Special effects in valleys 2.5.5 Rock movements in excavations 2.6 Weathering of rocks 2.6.1 Mechanical weathering 2.6.2 Chemical decomposition 2.6.3 Chemical weathering 2.6.3.1 Susceptibility of common minerals to chemical weathering 2.6.3.2 Susceptibility of rock substances to chemical weathering 2.6.4 Weathered rock profiles and their development 2.6.4.1 Climate and vegetation 2.6.4.2 Rock substance types and defect types and pattern 2.6.4.3 Time and erosion 2.6.4.4 Groundwater and topography 2.6.4.5 Features of weathered profiles near valley floors 2.6.5 Complications due to cementation 2.7 Chemical alteration 2.8 Classification of weathered rock 2.8.1 Recommended system for classification of weathered rock substance2.8.2 Limitations on classification systems for weathered rock 2.9 Rapid weathering 2.9.1 Slaking of mudrocks 2.9.2 Crystal growth in pores 2.9.3 Expansion of secondary minerals 2.9.4 Oxidation of sulphide minerals 2.9.4.1 Sulphide oxidation effects in rockfill dams – some examples 2.9.4.2 Possible effects of sulphide oxidation in rockfill dams 2.9.4.3 Sulphide oxidation – implications for site studies 2.9.5 Rapid solution 2.9.6 Surface fretting due to electro-static moisture absorption 2.10 Landsliding at dam sites 2.10.1 First-time and “reactivated’’ slides 2.10.1.1 Reactivated slides 2.10.1.2 First-time slides 2.10.2 Importance of early recognition of evidence of past slope instability at dam sites 2.10.3 Dams and landslides: Some experiences 2.10.3.1 Talbingo Dam 2.10.3.2 Tooma Dam 2.10.3.3 Wungong Dam 2.10.3.4 Sugarloaf Dam 2.10.3.5 Thomson Dam 2.11 Stability of slopes around storages 2.11.1 Vital slope stability questions for the feasibility and site selection stages 2.11.1.1 Most vulnerable existing or proposed project features, and parts of storage area? – Question 1 2.11.1.2 Currently active or old dormant landslides? – Questions 2 and 4 to 72.11.1.3 Areas where first-time landsliding may be induced (Questions 3 to 7) 2.11.1.4 What is the likely post failure velocity and travel distance? 2.11.1.5 What is the size of impulse waves which may be created? 2.12 Watertightness of storages 2.12.1 Models for watertightness of storages in many areas of non-soluble rocks 2.12.2 Watertightness of storage areas formed by soluble rocks 2.12.3 Features which may form local zones of high leakage, from any storage area 2.12.4 Watertightness of storages underlain by soils 2.12.5 Assessment of watertightness 2.12.5.1 Storages in non-soluble rock areas – assessment of watertightness 2.12.5.2 Storages in soluble rock areas – assessment of watertightness 2.12.5.3 Storages formed in soils – assessment of watertightness 2.12.6 Methods used to prevent or limit leakages from storages 3 Geotechnical questions associated with various geological environments 3.1 Granitic rocks 3.1.1 Fresh granitic rocks, properties and uses 3.1.2 Weathered granitic rocks, properties, uses and profiles 3.1.3 Stability of slopes in granitic rocks 3.1.4 Granitic rocks: check list 3.2 Volcanic rocks (intrusive and flow) 3.2.1 Intrusive plugs, dykes and sills 3.2.2 Flows 3.2.2.1 Flows on land 3.2.2.2 Undersea flows 3.2.3 Alteration of volcanic rocks 3.2.4 Weathering of volcanic rocks 3.2.5 Landsliding on slopes underlain by weathered basalt 3.2.6 Alkali-aggregate reaction 3.2.7 Volcanic rocks (intrusive and flow) check list of questions 3.3 Pyroclastics 13.3.1 Variability of pyroclastic materials and masses 3.3.2 Particular construction issues in pyroclastics 3.3.3 Pyroclastic materials – check list of questions 3.4 Schistose rocks 3.4.1 Properties of fresh schistose rock substances 3.4.2 Weathered products and profiles developed in schistose rock 3.4.3 Suitability of schistose rocks for use as filter materials, concrete aggregates and pavement materials 3.4.4 Suitability of schistose rocks for use as rockfill 3.4.5 Structural defects of particular significance in schistose rocks 3.4.5.1 Minor faults developed parallel and at acute angles to the foliation 3.4.5.2 Kink bands 3.4.5.3 Mica-rich layers 3.4.6 Stability of slopes formed by schistose rocks 3.4.7 Schistose rocks – check list of questions 3.5 Mudrocks 3.5.1 Engineering properties of mudrocks 3.5.2 Bedding-surface faults in mudrocks 3.5.3 Slickensided joints or fissures 3.5.4 Weathered products and profiles in mudrocks 3.5.5 Stability of slopes underlain by mudrocks 3.5.6 Development of unusually high pore pressures 3.5.7 Suitability of mudrocks for use as construction materials 3.5.8 Mudrocks – check list of questions 3.6 Sandstones and related sedimentary rocks 3.6.1 Properties of the rock substances 3.6.2 Suitability for use as construction materials 3.6.3 Weathering products 3.6.4 Weathered profile and stability of slopes 3.6.5 Sandstones and similar rocks – list of questions 3.7 Carbonate rocks 3.7.1 Effects of solution 3.7.1.1 Rock masses composed of dense, fine grained rock substances comprising more than 90% of carbonate (usually Category O) 3.7.1.2 Rock masses composed of dense fine grained rock substance containing 10% to 90% of carbonate (usually Category O) 3.7.1.3 Rock masses composed of porous, low density carbonate rock substance (usually Category Y) 3.7.2 Watertightness of dam foundations 3.7.2.1 Dams which have experienced significant leakage problems 3.7.3 Potential for sinkholes to develop beneath a dam, reservoir or associated works 3.7.4 Potential for continuing dissolution of jointed carbonate rock in dam foundations 3.7.5 Potential for continuing dissolution of aggregates of carbonate rock particles and of permeable carbonate substances (Category O carbonate, in each case) 3.7.6 Discussion – potential for continuing dissolution of carbonate rocks in foundations 3.7.6.1 Category O carbonate rocks 3.7.6.2 Category Y carbonate rocks 3.7.7 Potential problems with filters’ composed of carbonate rocks 3.7.7.1 Category O carbonate rocks 3.7.7.2 Category Y carbonate materials 3.7.8 Suitability of carbonate rocks for embankment materials 3.7.9 Suitability of carbonate rocks for concrete and pavement materials 3.7.10 Stability of slopes underlain by carbonate rocks 3.7.11 Dewatering of excavations in carbonate rocks 3.7.12 Carbonate rocks – check list of questions 3.8 Evaporites 3.8.1 Performance of dams built on rocks containing evaporites 3.8.2 Guidelines for dam construction at sites which contain evaporites 3.8.3 Evaporites – checklist of questions 3.9 Alluvial soils 3.9.1 River channel deposits 3.9.2 Open-work gravels 3.9.3 Oxbow lake deposits 3.9.4 Flood plain, lacustrine and estuarine deposits 3.9.5 Use of alluvial soils for construction 3.9.6 Alluvial soils, list of questions 3.10 Colluvial soils 3.10.1 Occurrence and description 3.10.1.1 Scree and talus 3.10.1.2 Slopewash soils 3.10.1.3 Landslide debris 3.10.2 Properties of colluvial soils 3.10.2.1 Scree and talus 3.10.2.2 Slopewash 3.10.2.3 Landslide debris 3.10.3 Use as construction materials 3.10.4 Colluvial soil – list of questions 3.11 Laterites and lateritic weathering profiles 3.11.1 Composition, thicknesses and origin of lateritic weathering profiles 3.11.2 Properties of lateritic soils 3.11.3 Use of lateritic soils for construction 3.11.4 Karstic features developed in laterite terrain 3.11.5 Recognition and interpretation of silcrete layer 3.11.6 Lateritic