Environmental Geomechanics A Recent Development in Geotechnical by pzs15406

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									Environmental Geomechanics: A Recent Development in
              Geotechnical Engineering



                    DR. D. N. SINGH
                      PROFESSOR
             Geotechnical Engineering Division
              Department of Civil Engineering
                     I.I.T. BOMBAY



               dns@civil.iitb.ac.in
           Civil Engineering

 "...to design and construct public works..."


                       Transformation



Practice of improving and maintaining the
built and natural environment to enhance
  the quality of life for present and the
           generations to follow
             Role of Civil Engineers
         “Designers and Builders of
          The Quality of Life…….”
Creators of the Civilised Society    Environment
Providing solutions to the needs of a developing global
population
Performers (on a world stage) as strategic thinkers and
global managers
Pillars of local Economies
Creating and maintaining complex infrastructure in
wealth creation
               Subject Organization
                 Geotechnical Engineering




          Geomechanics                         Environment
                               Challenge

                                                  Effect is more
Rock Mechanics       Soil Mechanics
                                                   pronounced


 Foundations      Retaining Structures      Seepage/Slopes/Dams
          Environmental Geomechanics
Genesis
    Population Explosion
    Industrialization
    Sluggish and “Don’t bother approach”
    Ignorance
    Human Greed

    Is a Philosophy put in practice to deal with

    under-ground “environment” & Problems associated with it

    Combination/Blend of
    Geotechnical Engg. and Environmental Engg.
        Waste Disposal Strategies

           Above ground storage


No protection                    Protected by
                               geologic materials




             Av erage water table
               Shallow trench burial

                                   Engineered
Backfill                  geological materials.




   B ackfill


                      wet period
                      av erage

                      dry period
                       Deep Disposal

   with backfill                             Protected by
                                                high-
retardation                                        geologic
material      Large boreholes 10 to 20 meters deep




                     Av erage water table

                                                     B ackfill
                 B ackfill
                                                     material
                             Unfrctured
                              clay ey                Protectiv e Geologic
                             depos its               material

                  W as te
                                                     W as te
                         Issues are

    • Ascertaining the quality of air, water, and land resources;
    • Transport, use, and disposal of hazardous wastes
    • water and wastewater treatment, and reuse.

     • Analysis and design of foundation systems, seepage
     control, earth dams and water resource structures,
     response of foundations and embankments to
        the ENVIRONMENTAL ACTIVITIES
 Man made industrialization/population explosion
Natural      earthquakes/(& to some extent other natural calamities).
       SCOPE of Environmental Geomechanics
Assessment of pollutants being discharged on/in the soil deposits
(Disposal/Handling/storage)

Process by which the pollutants travel in geo-environment
(Contaminant Transport)

Protection of ground water aquifers from contamination
(Containment)

Methods of cleaning the contaminated sites
(Remediation)

Methods of creating “Value added” products
(Recycling & Reuse)
            Specific Studies on
• Hazardous wastes
• Physical, Chemical, Mineralogical, Electrical and
  Thermal characterization
• Geoenvironmental hazards:
       Natural and man made
       Recycle and Reuse of Industrial waste(s)
• Role of Geotechnical engineering in environmental
  protection
• Surface and subsurface contamination
• Characterization of contaminated ground
• Geoenvironmental site investigation
• Site assessment technologies
                   Soil-Water-Environment Interaction

  The Natural                                               Man Made
                               Geomicrobiosphere
  Environment                                              Environment


                        The Particle Energy Field         Environmental
                                 Theory                   Geotechnical
                                                            Problems
   Requires knowledge from other Disciplines
Bacteriology     Biology             Chemical Engg.   Understanding of Soil
Climatology      Geohydrology        Geophysics           response to
Geochemistry Hydrogeology            Mechanics           Environments
Microgeology     Physico-Chemistry   Soil Science      (Short & long-term)
Soil Engineering Toxicology
                 The Natural Environment


Atmosphere
Biosphere

       Oxygen Cycle
       Nitrogen Cycle                The Cycle of Nature
       Carbon Cycle

Hydrosphere
Lithosphere


Geomicrobiosphere       Ecosphere
                       Man-made Environment


                Solid                           Liquid

Agricultural wastes

Human and Animal wastes

Industrial wastes

Mine wastes……Acid mine waste
(due to oxidation of Iron Sulphide (FeS2) or Pyrites to H2SO4)

Nuclear wastes

Construction Effects (Blasting/Dewatering/debris…)
   Soil Response to Environments

Soil structures (on/in/with)
Pore fluid characteristics
Soil-heat
Soil-Chemical
Soil Bacteria
Soil-Root
Soil-Electrical
Soil-Liquid (water)
                    Basic concepts of Analysis
  Most geotechnical projects occur in nature

           Long-term phenomenon


Soil is more sensitive and susceptible to environment
         than any other construction material

          Loading may greatly affect soil properties but not the only
          Parameter to be considered
                     Think of other factors:

                      Heat
                      Moisture (wet/Dry)
                      Pollution intrusion
     Classical Soil Mechanics: Some flaws
Specific gravity and Atterberg limits are constant
Void ratio and porosity as indicators of soil deformation
Water in the soil mass is mainly gravity water
       (need to consider Environmental water)
Flow through a soil mass is only due to hydrostatic potential
   (need to consider thermal/electrical/magnetic/chemical effects)

Constitutive models are arbitrarily chosen.
                     Stress-strain relationship
         Soil Classification: Controlling Parameters


               Grain-size distribution
  Present
               Soil Consistency (moisture content)
  scenario
               LL
(Parameters)   PL
               PI


               % Passing #200 Sieve
 Proposed      Specific surface
 scenario      pH in pore fluid
(Parameters)   Ion-exchange capacity
               Absorption & adsorption
               Thermal properties (Conductivity, diffusivity, specific heat)
               Dielectric constant (Electrical properties)
Environmental Geomechanics Laboratory @ IIT Bombay




     www.civil.iitb.ac.in/~dns

You are most welcome to Visit the laboratory

								
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