Principles of Engineering Geology

'Engineering geology' is one of those terms that invite definition. The American Geological Institute, for example, has expanded the term to mean 'the application of the geological sciences to engineering practice for the purpose of assuring that the geological factors affecting the location, design, construction, operation and mainten­ ance of engineering works are recognized and adequately provided for'. It has also been defined by W. R. Judd in the McGraw-Hill Encyclopaedia of Science and Technology as 'the application of education and experience in geology and other geosciences to solve geological problems posed by civil engineering structures'. Judd goes on to specify those branches of the geological or geo-sciences as surface (or surficial) geology, structural/fabric geology, geohydro­ logy, geophysics, soil and rock mechanics. Soil mechanics is firmly included as a geological science in spite of the perhaps rather unfortunate trends over the years (now happily being reversed) towards purely mechanistic analyses which may well provide acceptable solutions for only the simplest geology. Many subjects evolve through their subject areas from an interdisciplinary background and it is just such instances that pose the greatest difficulties of definition. Since the form of educational development experienced by the practitioners of the subject ulti­ mately bears quite strongly upon the corporate concept of the term 'engineering geology', it is useful briefly to consider that educational background.

1 Composition of Rocks.- 1.1 Origin and geological classification of rocks.- 1.2 Rock forming minerals.- 1.3 Clay minerals.- 1.4 Base exchange and water adsorption in clay minerals.- 1.5 Mineralogical identification.- 2 Rock Particles and Particle Systems.- 2.1 Rock particle classification.- 2.2 Typical rock particle systems.- 2.3 Physical properties of particulate systems.- 2.4 Permeability of particulate systems.- 2.5 Representation of stress in a soil mass.- 2.6 Effective stress.- 2.7 Frictional properties of rock particles.- 2.8 Soil deformation — drained granular media.- 2.9 Soil strength — drained granular media.- 2.10 Soil strength and deformation — clay soils.- 2.11 Pore pressure parameters.- 2.12 Rate of porewater pressure dissipation.- 2.13 The critical state concept.- 2.14 Limiting states of equilibrium.- 3 Clays and Clay Shales.- 3.1 Interparticle attraction and repulsion.- 3.2 Sediment formation and clay fabrics.- 3.3 Unstable clay fabrics.- 3.4 Glacial and periglacial clays.- 3.5 Depth — strength profiles.- 3.6 Macrostructure of overconsolidated clays and clay shales.- 3.7 Engineering influence of discontinuities in clay shales.- 3.8 Classification of clay shales.- 3.9 Consolidation and diagenetic considerations.- 3.10 Physical breakdown of shales.- 3.11 Suction pressure.- 3.12 Swelling pressure.- 3.13 Chemical and mineralogical analyses of clays.- 3.14 Relationship between mineralogy, geochemistry and geotechnical properties of clays and clay shales.- 4 Rock as a Material.- 4.1 Uniaxial strength.- 4.2 Uniaxial short-term deformation.- 4.3 Deformation mechanisms in rock.- 4.4 Complete stress — strain characteristics of rock in uniaxial compression.- 4.5 Effect of rate and duration of loading.- 4.6 Deformation and failure of rocks in triaxial compression.- 4.7 Failure criteria for rocks.- 4.8 Yield criteria.- 4.9 Rock dynamics.- 4.10 Wave transmission through rocks.- 4.11 Wave attenuation.- 4.12 Rock as a construction material.- 5 Preferred Orientation, Symmetry Concepts and Strength Anisotropy of some Rocks and Clays.- 5.1 Studies of the orientation density distribution of clay minerals and other associated minerals.- 5.2 X-ray texture goniometry.- 5.3 Symmetry concepts.- 5.4 Deformation paths.- 5.5 Deformation ellipsoid.- 5.6 Randomization.- 5.7 Symmetry elements and sub-fabrics.- 5.8 Crystallographic plane multiplicities and symmetry.- 5.9 Engineering influence of intrinsic anisotropy.- 5.10 Comparative degree of intrinsic anisotropy — mechanical evidence from rock experimentation.- 5.11 Intrinsic strength anisotropy of brittle and semi-brittle rocks comprising a dominant clay mineral control.- 5.12 Intrinsic anisotropy and sedimentation.- 5.13 Anisotropy of clay shales.- 5.14 Clay strength anisotropy.- 6 Rock Discontinuity Analysis.- 6.1 The engineering interest in discontinuities.- 6.2 Genesis and modification of fissures and slickensides.- 6.3 Controls on fissuring and fissure patterns.- 6.4 Classification of discontinuities.- 6.5 Character of discontinuities.- 6.6 Test specimen size—strength relationships.- 6.7 Stereographic representation of discontinuity data.- 6.8 Direct and inverse transformations from polar to equatorial angles.- 6.9 Linear orthogonal transformations.- 6.10 Eulerian angles.- 6.11 Discontinuity survey techniques.- 6.12 Analysis of discontinuity data.- 6.13 Influence of gouge material and surface roughness characteristics of discontinuities.- 6.14 Distributions.- 6.15 Orientation density distribution of discontinuities.- 6.16 Discontinuity shear stability in a polyaxial stress field.- 6.17 Shear strain energy concepts.- 6.18 Preliminary consideration of certain types of discontinuity structure in two dimensions.- 6.19 Statistics of scanlines through discontinuity distributions.- 6.20 Continuity.- 6.21 Preliminary shear stability analysis of discontinuities at the foundation interface of an earth or rock-fill dam.- 6.22 Stability of jointed rock in the foundation of an arch dam.- 6.23 Stability of a discontinuous clay surrounding an unlined tunnel.- 7 Site Investigation.- 7.1 Preliminary investigation.- 7.2 Aerial photographs.- 7.3 Terrain evaluation for highway projects.- 7.4 Geophysical exploration techniques.- 7.5 Seismic refraction surveying.- 7.6 Site exploration.- 7.7 Borehole logging.- 7.8 Sampling and testing.- 7.9 Site investigation reports.- 7.10 Mechanical tests in situ.- 7.11 Field monitoring techniques.- 7.12 Use of field seismic techniques in engineering geology.- 7.13 Analysis of ground vibrations.- 7.14 Marine geotechnical exploration.- 7.15 Mining subsidence.- 7.16 Probability theory in site investigation.- 7.17 What is ‘safety’ in soil and rock mechanics?.- 8 Groundwater.- 8.1 Types of subsurface water.- 8.2 Groundwater flow.- 8.3 Seepage forces.- 8.4 Drainage and drain wells.- 8.5 Permeability tests — rock.- 8.6 Permeability tests — soils.- 8.7 Economic exploitation of groundwater.- 8.8 Ownership of groundwater and permitted abstractions.- 8.9 Groundwater exploration.- 8.10 Regional investigations.- 8.11 Simulation of groundwater regimes.- 8.12 Well losses.- 8.13 Improving aquifer yield.- 8.14 Groundwater quality.- 9 Stability of Soil Slopes.- 9.1 Planar slides.- 9.2 Circular failure surfaces.- 9.3 Slope stability case histories.- 9.4 Simple wedge method of analysis.- 9.5 Use of design curves.- 9.6 Pore pressure ratio.- 9.7 Clay slopes and shear strength parameters.- 9.8 Slope angle measurements in clays and clay shales.- 9.9 Classification of gravitational mass movements in clay.- 9.10 Rock breakdown and landform development.- 9.11 Geomorphological classification of slope profile development.- 9.12 General methods of preventing slope failure.- 9.13 Highway slopes.- 9.14 Protection against coastal erosion.- 10 Rock Slope Stability.- 10.1 Geomorphological classification of rock slope instabilities.- 10.2 Classification of rock masses.- 10.3 Character of joints in rock masses.- 10.4 Engineering recognition of rock failure modes.- 10.5 Surface roughness of joints.- 10.6 Discontinuity roughness classification.- 10.7 Planar sliding and the friction cone concept.- 10.8 Instability on intersecting joint planes.- 10.9 Influence of discontinuity orientation distributions.- 10.10 Seismic influences on stability with respect to sliding.- 10.11 Instability caused by block overturning.- 10.12 General rock slope design curves.- 10.13 Slopes in highway cuttings and embankments.- 11 Ground Improvement.- 11.1 Shallow compaction.- 11.2 Deep compaction.- 11.3 Pre-loading and consolidation.- 11.4 Sand drains.- 11.5 Grout treatment.- 11.6 Fissure grouting.- 11.7 Hydrofracture.- 11.8 Cavity grouting.- 11.9 Electro-chemical stabilisation.- 11.10 Groundwater freezing.- 11.11 Bentonite suspension.- 11.12 Ground anchors.- 12 Water Resources, Reservoirs and Dams.- 12.1 Water requirements in England and Wales.- 12.2 Planning of water resources.- 12.3 Conjunctive use schemes.- 12.4 Flood and dam design parameters.- 12.5 Channel protection.- 12.6 Design capacity of a storage reservoir.- 12.7 Air-photo interpretation for catchment development.- 12.8 Geological influences upon the selection of reservoir sites.- 12.9 Foundation investigations.- 12.10 Water movement into and out of a reservoir.- 12.11 Synthetic flow generation techniques.- 12.12 Dam foundations.- 12.13 Classification of dam types according to their purpose, construction and foundation geology.- 12.14 Long term stability of earth dams.- 12.15 Dam seismicity.- References.- Supplementary References.- Author Index.