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Environmental Geomechanics: A Recent Development in Environmental Geomechanics: A Recent Development in Geotechnical EngineeringGeotechnical Engineering
DR. D. N. SINGHDR. D. N. SINGHPROFESSORPROFESSOR
Geotechnical Engineering DivisionGeotechnical Engineering DivisionDepartment of Civil EngineeringDepartment of Civil Engineering
I.I.T. BOMBAYI.I.T. BOMBAY
dns@civil.iitb.ac.in
"...to design and construct public works..."
Civil Engineering
Practice of improving and maintaining the built and natural environment to enhance
the quality of life for present and the generations to follow
Transformation
Role of Civil Engineers
“Designers and Builders ofThe 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
Rock MechanicsRock Mechanics
FoundationsFoundations Retaining StructuresRetaining Structures Seepage/Slopes/DamsSeepage/Slopes/Dams
Soil MechanicsSoil Mechanics
GeomechanicsGeomechanics EnvironmentEnvironment
Geotechnical EngineeringGeotechnical Engineering
Challenge
Effect is morepronounced
Environmental GeomechanicsGenesis
Population ExplosionIndustrializationSluggish and “Don’t bother approach”IgnoranceHuman 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.
Average water table
Waste Disposal Strategies
Above ground storage
No protection Protected by geologic materials
wet period
average
dry period
Backfill
Shallow trench burial
Engineered Backfill geological materials.
Deep Disposal
with backfill Protected by high-
retardation geologic material
Average water table
Backfill
Waste
Large boreholes 10 to 20 meters deep
Protective Geologic material
Backfillmaterial
Waste
deposits
Unfrcturedclayey
Issues areIssues 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 Natural earthquakes/(& to some extent other natural calamities).
industrialization/population explosion
SCOPE of Environmental Geomechanics
Protection of ground water aquifers from contamination(Containment)(Containment)
Assessment of pollutants being discharged on/in the soil deposits (Disposal/Handling/storage)(Disposal/Handling/storage)
Process by which the pollutants travel in geo-environment (Contaminant Transport)(Contaminant Transport)
Methods of cleaning the contaminated sites(Remediation)(Remediation)
Methods of creating “Value added” products(Recycling & Reuse)(Recycling & Reuse)
Specific Studies on
• Hazardous wastes• Physical, Chemical, Mineralogical, Electrical and Thermal characterization• Geoenvironmental hazards:
Natural and man madeRecycle 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 Environment
Geomicrobiosphere Man Made Environment
The Particle Energy Field Theory
Environmental Geotechnical
Problems
Understanding of Soil response to
Environments
(Short & long-term)
Requires knowledge from other DisciplinesBacteriology Biology Chemical Engg.
Climatology Geohydrology Geophysics
Geochemistry Hydrogeology Mechanics
Microgeology Physico-Chemistry Soil Science
Soil Engineering Toxicology
The Natural Environment
AtmosphereBiosphere
Oxygen CycleNitrogen CycleCarbon Cycle
HydrosphereLithosphere
Geomicrobiosphere Ecosphere
The Cycle of Nature
Man-made Environment
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…)
Solid Liquid
Soil Response to Environments
Soil structures (on/in/with)Pore fluid characteristicsSoil-heatSoil-ChemicalSoil BacteriaSoil-RootSoil-ElectricalSoil-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:
HeatMoisture (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 distributionSoil Consistency (moisture content)LLPLPI
Present scenario
(Parameters)
Proposed scenario
(Parameters)
% Passing #200 SieveSpecific surfacepH in pore fluidIon-exchange capacityAbsorption & adsorptionThermal 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 laboratoryYou are most welcome to Visit the laboratory
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