Geotech Engg Part 1

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Transcript of Geotech Engg Part 1

  • CE 100: Introduction to Civil and Environmental EngineeringGeotechnical EngineeringNov 3rd 2013

    Lecture 7

  • What is Geotechnical Engineering?Geotechnical engineering involves investigation and engineering evaluation of -materials, -their systems-structural foundations and -other civil engineering works.

    It also involves applications of the -principles of the soil mechanics - construction techniques and -performance evaluation of civil engineering work influenced by earth materials.

    It requires comprehensive understanding of the elements of geologic environment.

  • Which type of information is needed in Geotechnical Engineering?Nature and composition of Soil and rock. Ground water condition Soil stresses: stress history, over-consolidation, lateral stresses. Confined compression of soils. Soil suction, collapse and swelling. Soil strength and deformability:

  • GEOTECHNICAL APPLICATIONSFoundationsRetaining wallsEarthern DamsConcrete DamsGeomembrane/geosynthetics Trenchless technology


  • Foundation EngineeringFoundation engineering is an art ofselecting, designing and constructing the elementsthat transfer the weight of structure to theunderlying soil or rock.

    Before designing a foundation, the engineer must have a reasonably accurate conception of

    the physical properties and

    the arrangement of the underlying materials.

  • *Retaining Walls~ for retaining soils from spreading laterally

  • *Earth Dams~ for impounding water

  • *Concrete Dams

  • *Concrete DamsThree Gorges Dam, Hong Kong

  • *Sheet Piles~ resist lateral earth pressures~ used in excavations, waterfront structures, ..~ in temporary works

  • *Geofabrics~ used for reinforcement, separation, filtration and drainage in roads, retaining walls, embankments

  • Geosynthetics/Geomembrane

  • *Geosynthetics/GeomembraneWaste Disposal in Landfills

  • *Reinforced Earth Walls~ using geofabrics to strengthen the soil

  • Trenchless Technology


    *******Fig 1: ref IMME 2012**Open trenching (direct burial) is, moreoften than not, the preferred method of pipe installation. However, the open trench method creates significantdisturbance, especially in urban areas, and might not be feasible due to difficult ground conditions, existingunderground utilities and structures, environmental sensitivities, and the presence of river, railroad, or highwaycrossings. Because of these constraints, decision makers (facility owners, planners, and engineers alike), must beaware of the trenchless technologies available as alternatives to open trench pipe installation.

    1. Pipe Jacking & Microtunneling,2. Horizontal Auger Boring (HAB), and3. Horizontal Directional Drilling (HDD).Ref: