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• Engineering geology


  That of applied science which deals with the application of geology for a safe, stable and economic design and construction of a civil engineering project
• Engineering geology


  • It provides information to engineering through description of the structure and attributes of rocks connected with engineering work
  • It identifies and evaluates natural hazards like landslides and earthquakes that may affect the success of an engineering project
  • The engineering geologist is charged with the responsibility of interpreting the geologic data and providing a conceptual model representing the morphology and engineering-geologic classification of each rock unit
• Soil mechanics


  The study of the engineering mechanics and physical properties of soil
• Geotechnical engineering


  The application of civil engineering technology to the aspects of earth, which may include both soil and rock
• Geotechnical engineering


  • It combines the knowledge of geology, soil mechanics, rock mechanics and structural engineering to design and construct foundations or similarly related structures for civil engineering and other construction
  • It is the most empirical discipline among other disciplines of civil engineering due to the unpredictable nature of the material it deals with (soil and rock)
• Scope of geology in civil engineering

  • Engineering geology is essential
  • Application of geological knowledge in planning, designing and construction of big civil engineering projects
  • Enabling civil engineers to understand the engineering implications of geological conditions
  • Enabling geologists to understand the nature of the geological information that is absolutely essential for a safe design and construction of a civil engineering project
• Major activities of civil engineers where the scope of geology can be studied

  • Construction
  • Water resources development
  • Town and regional planning
• Main and allied branches of geology

  • Physical geology
  • Mineralogy
  • Petrology
  • Structural geology
  • Stratigraphy
  • Economic geology
  • Engineering geology
  • Mining geology
  • Geophysics
  • Geohydrology
  • Geochemistry
• Physical geology


  Deals with the different physical features of the earth, changes occurring on the earth surface, geological work of natural agents, and natural phenomena
• Mineralogy


  Deals with the study of minerals, their mode of formation, composition, occurrence, types, association, properties and uses
• Petrology


  Deals with the study of rocks, their mode of formation, structure, texture, composition, occurrence, and types
• Structural geology


  Deals with the deformations, dislocations and disturbances in rocks under the influence of tectonic forces, and the resulting geological structures like folds, faults, joints and unconformities
• Stratigraphy


  Deals with the study of the earth's history through the sedimentary rock record
• Economic geology


  Deals with the details of economic minerals, their mode of formation, occurrence, classification, association, varieties, concentration, properties, and uses
• Engineering geology


  Deals with the application of geological knowledge in the field of civil engineering, for execution of safe, stable and economic constructions
• Mining geology


  Deals with the application of geological knowledge in the field of mining, including mineral exploration, estimation and extraction
• Geophysics


  Deals with the study of physical properties like density and magnetism of the earth or its parts, and their application in solving civil engineering problems
• Geohydrology


  Deals with the occurrence, movement and nature of groundwater in an area, and its application in groundwater investigations
• Geochemistry


  Deals with the occurrence, distribution, abundance, mobility etc. of different elements in the earth's crust
• Weathering


  The process of breaking down rocks by mechanical and chemical processes into smaller pieces
• Factors affecting weathering

  • Nature of rocks
  • Length of time
  • Climate
• Mechanical weathering


  The physical breakdown of rock masses under the attack of certain atmospheric agents, like expansion and contraction due to temperature changes
• Chemical weathering


  The transformation of original rock minerals into new minerals by chemical reaction with atmospheric gases
• Weathered products/Residual soils


  • Residual soils - soils formed by weathered products at their place of origin
  • Transported soils - soils produced by weathering of rocks transported by physical processes to other places, including glacial, alluvial, lacustrine, marine, aeolian, and colluvial soils
  • Organic soils - derived from the decomposition of organic materials
• Wind erosion


  The detachment, transportation and redeposition of soil particles by wind, caused by deflation (simple removal of loose particles) and abrasion (sand-blasting of larger rock structures)
• Weathering of feldspar, ferromagnesians, and micas

  • Gives the plasticity property to soils
• Wind


  The movement of the atmosphere in a direction parallel to the earth surface
• Wind erosion


  The detachment, transportation and redeposition of soil particles by wind
• Wind erosion processes


  1. Deflation

  2. Abrasion
• Deflation


  Simple removal of the loose sand and dust sized particles from an area, by fast moving winds
• Abrasion


  The wind loaded with particles attains a considerable erosive power which helps in eroding the rock surfaces by rubbing and grinding actions
• Types of Aeolian soil

  • Sand dunes
  • Loess
• Sand dunes


  • Huge heaps of sand formed by the natural deposition of windblown sand
  • Sometimes of characteristics and recognizable shape
  • Can migrate from one place to another due to change in the direction and velocity of wind
• Types of active dunes

  • Barchan or crescent shaped dunes
  • Transverse dunes
  • Longitudinal dunes
• Barchan dunes


  • Triangular in section with the steep side facing away from the wind direction and inclined at an angle of about 30° to 33° to the horizontal
  • The gently sloping side lies on the windward side, and makes an angle of about 10 to 15° with the horizontal

  
• Transverse dunes


  Similar to barchans in section but in plan it is not curved like barchans such that its longer axis is broadly transverse to the direction of the prevailing winds
• Longitudinal dunes


  Elongated ridges of sand with their longer axis broadly parallel to the direction of the prevailing wind
• Loess


  A fine grained Aeolian soil characterized by its nearly uniform grain size, predominantly silt, and by its low density
• Highway cuts through loess deposits usually resemble those made in rock in that this soil will stand on a nearly vertical slope, whereas it is readily eroded by rain water if flatter slopes are used
• If an engineer is compelled to select sites with moving dunes, special methods should be adopted to check the motion of the moving dunes, such as constructing windbreaks or growing vegetation on the surrounding areas