Preface Acknowledgements About the author Scales, plotting conventions for graphs and reference lists List of abbreviations and mathematical symbols 1 HISTORICAL REVIEW OF THE DEVELOPMENT OF UNSATURATED SOIL MECHANICS 1.1 Historical progress in unsaturated soil mechanics literature: Karl Terzaghi’s four books 1.2 Meetings, documents and books that were critical in establishing unsaturated soil mechanics as a sub-discipline of soil mechanics 1.2.1 Matrix suction 1.2.2 Solute (or osmotic) suction 1.3 Progress in disseminating knowledge of unsaturated soil mechanics via basic soil mechanics text books 1.4 The special problem of unsaturated soils References Plate 2 DETERMINING EFFECTIVE STRESSES IN UNSATURATED SOILS2.1 The definition of an unsaturated soil 2.2 Interaction of pore air and pore water 2.3 The use of elevated pore-air pressures in the measurement of pore-water pressures (the axis translation technique) (Bishop & Blight, 1963) 2.4 The suction-water content curve (SWCC) (Blight, 2007) 2.4.1 Hysteresis in a saturated soil 2.4.2 Hysteresis in drying soils 2.4.3 Direct comparison between a consolidation curve and a SWCC 2.4.4 Hysteresis in compacted soils and the effect of particle size distribution 2.4.5 SWCCs extending to very dry soils, or high suctions 2.4.6 Empirical expressions for predicting SWCCs 2.4.7 The effect of soil variability on SWCCs and SWCCs measured by means of in situ tests 2.5 The characteristics of the effective stress equation for unsaturated soils (Bishop & Blight, 1963) 2.5.1 Evaluating the Bishop parameter ? or the Fredlund parameter ? b 2.5.2 Evaluating ? from the results of various types of sheartest, assuming that the equivalent test result for the saturated soil represents true effective stresses 2.5.3 Evaluating ? from compression, swelling and swelling pressure tests on the assumption that true effective stress behaviour of the unsaturated soil is represented by that of the same soil when saturated (Blight, 1965) 2.5.3.1 Isotropic compression 2.5.3.2 Isotropic swell 2.5.3.3 Swelling pressure 2.5.4 Summary of ? values from isotropic compression, swell and swelling pressure 2.5.5 The effect of stress path on values of ? 2.5.6 The ? parameter for compression of a collapsing sand 2.5.7 The parameter ? for extremely high values of suction 2.6 Incremental methods of establishing s I and ? 2.6.1 Shear strength 2.6.2 Volume change 2.6.3 Summary 2.7 Empirical methods of estimating parameter ? 2.8 The limits of effective stress in dry soils (Blight, 2011) 2.8.1 The experiment 2.8.2 The conclusionReferences Appendix A2: Equation for the solution of a bubble in a compressible container Plate 3 MEASURING AND CONTROLLING SUCTION 3.1 Direct or primary measurement of suction 3.1.1 Preparing the fine-pored ceramic3.1.2 De-airing and testing fine-pored ceramic filters for air entry 3.1.3 The effects of capillarity on the de-airing process 3.1.4 Typical responses of tensiometers 3.1.5 Direct measurement of suctions exceeding 100 kPa 3.1.6 Null-flow methods of measuring suction3.2 Indirect or secondary methods of measuring water content or suction 3.2.1 Filter paper 3.2.2 Thermal conductivity sensor 3.2.3 Electrical conductivity sensor 3.2.4 Time domain reflectometry (TDR) 3.2.5 Dielectric sensors 3.3 Thermodynamic methods of controlling or measuring suction 3.3.1 Control of relative humidity 3.3.2 Measuring relative humidity 3.3.2.1 Thermocouple psychrometer 3.3.2.2 Transistor psychrometer 3.3.2.3 Chilled-mirror psychrometer 3.4 A commentary on the use of the Kelvin equation as a measure of total suction 3.5 Use of direct and indirect suction measurements in the field 3.5.1 A comparison of field measurements of a suction profile using thermocouple psychrometers, contact and noncontact filter paper (van der Raadt, et al., 1987) 3.5.2 Near-surface changes of water content as a result of evapotranspiration (Blight, 2008) 3.5.3 A comparison of field measurements of suction by means of thermocouple psychrometers, gypsum blocks and glass fibre mats (Harrison & Blight, 2000) 3.5.4 Use of tensiometers to monitor the rate of infiltration of surface flooding into unsaturated soil strata (Indrawan, et al., 2006) 3.5.5 Use of suction gradients measured by gypsum blocks to examine the patterns of water flow in a stiff fissured clay (Blight, 2003) 3.5.6 Use of high tension tensiometers to monitor suctions in a test embankment (Mendes, et al., 2008) 3.5.7 Effect of covering the surface of a slope cut in residual granite soil with a capillary moisture barrier to stabilize the slope against surface sloughing (Rahardjo, et al., 2011) 1323.6 A different application for measuring or controlling suction: Controlling alkali–aggregate reaction (AAR) in concrete, (Blight & Alexander, 2011) 3.6.1 Controlling alkali–aggregate reaction (AAR) in concrete References Plates 4 INTERACTIONS BETWEEN THE ATMOSPHERE AND THE EARTH’S SURFACE: CONSERVATIVE INTERACTIONS – INFILTRATION, EVAPORATION AND WATER STORAGE 4.1 The atmospheric water balance 4.2 The soil water balance 4.3 Measuring infiltration (I) and runoff (RO) 4.4 Estimating evapotranspiration by solar energy balance 4.5 Difficulties in applying the energy balance to estimating evaporation 4.5.1 Field experiments using a large cylindrical pan set into the ground surface (Blight, 2009a) 4.5.2 Field measurement of the water balance for a landfill 4.5.3 Evaporation from experimental landfill capping layers 4.5.4 Evaporation from a grassed, fissured clay surface (Clarens, South Africa) 4.5.5 Near-surface movement of water during evapotranspiration 4.5.6 Drying of tailings beaches deposited on tailings storage facilities 4.6 Fundamental mechanisms of evaporation from water and soil surfaces 4.6.1 Water or soil heat as sources and drivers of evaporation 4.6.2 The role of wind energy 4.7 Evaporation from unsaturated sand and the effect of vegetation – the efficiency factor ? 4.8 Fundamental mechanisms of evaporation – discussion 4.9 Estimating evapotranspiration by means of lysimeter experiments 4.10 Depth of soil zone interacting with the atmosphere (also see section 4.5.5) 4.11 Recharge of water table and leachate flow from waste deposits 4.12 Estimating and measuring water storage capacity (S) for active zone 4.13 Seasonal and longer term variations in soil water balance 4.14 Consequences of a changing soil water balance 4.14.1 Effects on soil strength of a falling water table (also see section 8.8.1) 4.14.2 Effects of a rising water table – surface heave (also see section 8.6.2) 4.15 Cracking and fissuring of soil resulting from evaporation or evapotranspiration at the surface 4.15.1 Stresses in a shrinking soil 4.15.2 Cracking in a shrinking soil 4.15.3 Formation of shrinkage cracks at the surface 4.15.4 Formation of shrinkage cracks at depth 4.15.5 Characteristics of cracking observed in soil profiles 4.15.6 The formation of swelling fissures 4.15.7 Fissures in profiles that seasonally shrink and swell 4.15.8 Spacing of cracks on the surface 4.16 Damage to road pavements by upward migration of soluble salts 4.17 Root barriers to protect foundations of buildings from desiccating effects of tree roots (Blight, 2011) 4.17.1 Installation of root barriers 4.17.2 Effect of felling the tree 4.17.3 Examination of the exhumed root barriers 4.17.4 Conclusions 4.18 Use of an unsaturated soil layer to insulate flat (usually concrete) roofs (Gwiza, 2012) 4.19 Practical examples involving infiltration, evaporation and water storage 4.19.1 The infiltrate, store and evaporate (ISE) landfill cover layer (Blight & Fourie, 2005) (also see Fig. 4.11) 4.19.1.1 The influence of climate on landfilling practice 4.19.1.2 Dry tomb versus bioreactor 4.19.1.3 Water content of incoming waste 4.19.1.4 Stabilization in arid and semi-arid conditions 4.19.1.5 Evaporation from a landfill surface 4.19.1.6 Infiltrate-stabilize-evapotranspire (ISE) landfill covers 4.19.1.7 Field tests of ISE caps under summer and winter rainfa
